diff --git a/Makefile b/Makefile
index 900babb..bdfb1ba 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 CC=gcc
 CFLAGS=-Wall -Isrc/include -DDEBUG -g
 #LDFLAGS=-lm
-SRC=src/sort.c src/random.c src/bubble_sort.c src/timer.c src/count_sort.c src/quick_sort.c src/bitonic_sort.c src/selection_sort.c
+SRC=src/sort.c src/random.c src/bubble_sort.c src/timer.c src/count_sort.c src/quick_sort.c src/merge_sort.c src/bitonic_sort.c src/selection_sort.c
 OBJ=$(SRC:.c=.o)
 
 all: sort informe
diff --git a/README.md b/README.md
index d034e72..b5f83e9 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,20 @@
 # Sort
-Una programa que deja ejecutar varios algoritmos de ordenamiento.
\ No newline at end of file
+Una programa que deja ejecutar varios algoritmos de ordenamiento con el próposito de de comprobar la diferencia en rendamiento de los algoritmos.
+
+## Autores
+Christopher Cromer
+
+Rodolfo Cuevas
+
+## Compilar
+Hay tres blancos disponible para usar con GNU Make:
+
+	make sort
+Compilar el programa
+
+	make test
+Comprobar que los algoritmos y programa corren como esperado
+
+	make informe
+Compilar el informe si pdflatex está disponible en el sistema
+
diff --git a/src/count_sort.c b/src/count_sort.c
index 43d121c..0135485 100644
--- a/src/count_sort.c
+++ b/src/count_sort.c
@@ -13,6 +13,7 @@
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -25,7 +26,15 @@ void count_sort(int *array, int n) {
 	int i;
 	int j;
 	int *temp = malloc(sizeof(int) * n);
+	if (temp == NULL) {
+		fprintf(stderr, "Error: Out of heap space!\n");
+		exit(5);
+	}
 	int *count = malloc(sizeof(int) * n);
+	if (count == NULL) {
+		fprintf(stderr, "Error: Out of heap space!\n");
+		exit(5);
+	}
 	memcpy(temp, array, sizeof(int) * n);
 	for (i = 0; i < n - 1; i++) {
 		for (j = i + 1; j < n; j++) {
diff --git a/src/include/merge_sort.h b/src/include/merge_sort.h
new file mode 100644
index 0000000..1701ff0
--- /dev/null
+++ b/src/include/merge_sort.h
@@ -0,0 +1,21 @@
+/*
+ * Copyright 2018 Christopher Cromer
+ * Copyright 2018 Rodolfo Cuevas
+ *
+ * Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _SORT_MERGE
+	#define _SORT_MERGE
+	void merge_sort(int *array, int n);
+	void merge_sort_run(int *array, int *temp, int left, int right);
+	void merge(int *array, int *temp, int prev_left, int prev_middle, int right);
+#endif
diff --git a/src/merge_sort.c b/src/merge_sort.c
new file mode 100644
index 0000000..e4ddbbb
--- /dev/null
+++ b/src/merge_sort.c
@@ -0,0 +1,80 @@
+/*
+ * Copyright 2018 Christopher Cromer
+ * Copyright 2018 Rodolfo Cuevas
+ *
+ * Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <stdlib.h>
+#include "merge_sort.h"
+
+/**
+ * Usar el algoritmo de merge sort
+ * @param array El array a ordenar
+ * @param n El tamaño del array
+ */
+void merge_sort(int *array, int n) {
+	int *temp = malloc(sizeof(int)* n);
+	merge_sort_run(array, temp, 0, n - 1);
+	free(temp);
+}
+
+/**
+ * Correro el merge sort recursivamente
+ * @param array El array a ordenar
+ * @param temp Un array temporario para trabajar
+ * @param left El lado izquerda a ordenar
+ * @param right El lado derercha a ordenar
+ */
+void merge_sort_run(int *array, int *temp, int left, int right) {
+	if (left != right) {
+		int middle = (left + right) / 2;
+		merge_sort_run(array, temp, left, middle);
+		merge_sort_run(array, temp, middle + 1, right);
+		merge(array, temp, left, middle + 1, right);
+	}
+}
+
+/**
+ * Unir los resultados de "dividir y conquistar" de merge sort
+ * @param array El array a ordenar
+ * @param temp Un array temporario para trabajar
+ * @param prev_left El lado izquerda anterior
+ * @param prev_middle La particion de medio anterior
+ * @param right El lado derecha
+ */
+void merge(int *array, int *temp, int prev_left, int prev_middle, int right) {
+	int i = 0;
+	int left = prev_left;
+	int middle = prev_middle - 1;
+	int far_right = right - left + 1;
+
+	while (prev_left <= middle && prev_middle <= right) {
+		if (array[prev_left] < array[prev_middle]) {
+			temp[i++] = array[prev_left++];
+		}
+		else {
+			temp[i++] = array[prev_middle++];
+		}
+	}
+
+	while (prev_left <= middle) {
+		temp[i++] = array[prev_left++];
+	}
+
+	while (prev_middle <= right) {
+		temp[i++] = array[prev_middle++];
+	}
+
+	for (i = 0; i < far_right; i++) {
+		array[left + i] = temp[i];
+	}
+}
diff --git a/src/quick_sort.c b/src/quick_sort.c
index aa56d78..95a0274 100644
--- a/src/quick_sort.c
+++ b/src/quick_sort.c
@@ -13,22 +13,30 @@
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+/**
+ * Usar el algoritmo de quick sort
+ * @param array El array a ordenar
+ * @param n El tamaño del array
+ */
 void quick_sort(int *array, int n) {
-	if(n<2)return;
+	if(n < 2) {
+		return;
+	}
 	int i;
 	int j;
 	int temp;
-	int pivote=array[n/2];
-	for(i=0,j=n-1;;i++,j--){
-		while(array[i] < pivote) i++;
-		while(array[j] > pivote) j--;		
-		if(i>=j)break;
-		temp=array[i];
+	int pivote = array[n / 2];
+	for (i =0, j = n - 1;; i++, j--) {
+		while (array[i] < pivote) i++;
+		while (array[j] > pivote) j--;
+		if (i >= j) {
+			break;
+		}
+		temp = array[i];
 		array[i] = array[j];
-		array[j] = temp;	
+		array[j] = temp;
 	}
 
-	quick_sort(array,i);
-	quick_sort(array+i,n-i);
+	quick_sort(array, i);
+	quick_sort(array + i, n - i);
 }
-
diff --git a/src/sort.c b/src/sort.c
index c79c6fc..8e49ddb 100644
--- a/src/sort.c
+++ b/src/sort.c
@@ -17,6 +17,8 @@
 #include <stdlib.h>
 #include <getopt.h>
 #include <string.h>
+#include <errno.h>
+#include <limits.h>
 #include "random.h"
 #include "timer.h"
 #include "bubble_sort.h"
@@ -24,13 +26,17 @@
 #include "quick_sort.h"
 #include "bitonic_sort.h"
 #include "selection_sort.h"
+#include "merge_sort.h"
 
 #define SORT_VERSION "1.0.0"
 
 /**
- * El array a ordenar
+ * El array desordenado
  */
 static int *unordered_array;
+/**
+ * El array a ordenar
+ */
 static int *work_array;
 
 /**
@@ -73,26 +79,63 @@ void print_array(int *array, int n) {
  * @return Retorna 1 si es exitosa ó 0 si falla
  */
 int read_buffer(int *variable) {
-	char buffer[12];
+	char buffer[32];
+	char *check;
 	while (1) {
-		if (fgets(buffer, 12, stdin) != NULL) {
+		if (fgets(buffer, 32, stdin) != NULL) {
 			if (buffer[strlen(buffer) - 1] == '\n') {
 				buffer[strlen(buffer) - 1] = '\0';
 				break;
 			}
 		}
 	}
-	char **check = malloc(sizeof(char**));
-	long input = strtol(buffer, check, 10);
-	if (*check[0] == '\0') {
-		free(check);
+	errno = 0;
+	long input = strtol(buffer, &check, 10);
+	if (buffer == check) {
+		// Empty
+		return 0;
+	}
+	else if (errno == ERANGE && input == LONG_MIN) {
+		// Overflow
+		return 0;
+	}
+	else if (errno == ERANGE && input == LONG_MAX) {
+		// Underflow
+		return 0;
+	}
+	else if (errno == EINVAL) {  /* not in all c99 implementations - gcc OK */
+		// Base contains unsupported value
+		// This check is not in all c99 implementations, but does exist in gcc
+		return 0;
+	}
+	else if (errno != 0 && input == 0) {
+		// Unspecified error
+		return 0;
+	}
+	else if (errno == 0 && !*check) {
+		// Valid number
+		if (input > INT_MAX || input < INT_MIN) {
+			fprintf(stderr, "Error: n tiene que ser menor de 2147483648 y mayor de -2147483649!\n");
+			return 0;
+		}
 		*variable = (int) input;
 		return 1;
 	}
-	else {
-		free(check);
+	else if (errno == 0 && *check != 0) {
+		// Contains non number characters
 		return 0;
 	}
+	else {
+		return 0;
+	}
+}
+
+/**
+ * Imprimir un mensaje y salir si n es invalido
+ */
+void print_invalid_n() {
+	fprintf(stderr, "Error: El valor de n es invalido!\n");
+	exit(7);
 }
 
 /**
@@ -109,7 +152,9 @@ void cleanup() {
  * @return Retorna el codigo de error o 0 por exito
  */
 int main (int argc, char **argv) {
-	long long i;
+	char *check = NULL;
+	long ninput = 0;
+	int i;
 	int n = 10;
 	int elegir = 0;
 	int imprimir = 0;
@@ -170,10 +215,44 @@ int main (int argc, char **argv) {
 				selection = 1;
 				break;
 			case 'n':
-				n = atol(optarg);
-				if (n <= 1) {
-					fprintf(stderr, "Error: n tiene que ser mayor de 1!\n");
-					return 3;
+				errno = 0;
+				ninput = strtol(optarg, &check, 10);
+				if (optarg == check) {
+					// Empty
+					print_invalid_n();
+				}
+				else if (errno == ERANGE && ninput == LONG_MIN) {
+					// Overflow
+					print_invalid_n();
+				}
+				else if (errno == ERANGE && ninput == LONG_MAX) {
+					// Underflow
+					print_invalid_n();
+				}
+				else if (errno == EINVAL) {  /* not in all c99 implementations - gcc OK */
+					// Base contains unsupported value
+					// This check is not in all c99 implementations, but does exist in gcc
+					print_invalid_n();
+				}
+				else if (errno != 0 && ninput == 0) {
+					// Unspecified error
+					print_invalid_n();
+				}
+				else if (errno == 0 && optarg && !*check) {
+					// Valid number
+					if (ninput > INT_MAX || ninput < INT_MIN) {
+						fprintf(stderr, "Error: n tiene que ser menor de 2147483648!\n");
+						return 6;
+					}
+					n = (int) ninput;
+					if (n <= 1) {
+						fprintf(stderr, "Error: n tiene que ser mayor de 1!\n");
+						return 3;
+					}
+				}
+				else if (errno == 0 && optarg && *check != 0) {
+					// Contains non number characters
+					print_invalid_n();
 				}
 				break;
 			case 'e':
@@ -199,27 +278,42 @@ int main (int argc, char **argv) {
 	}
 
 	unordered_array = malloc(sizeof(int) * n);
+	if (unordered_array == NULL) {
+		fprintf(stderr, "Error: Out of heap space!\n");
+		exit(5);
+	}
 	work_array = malloc(sizeof(int) * n);
+	if (work_array == NULL) {
+		fprintf(stderr, "Error: Out of heap space!\n");
+		exit(5);
+	}
 	atexit(cleanup);
 
 	// Llenar el array con valores para ordenar después
 	for (i = 0; i < n; i++) {
 		if (elegir) {
 			opt = 0;
-			fprintf(stdout, "Elegir elemento %lli: ", i + 1);
+			fprintf(stdout, "Elegir elemento %d: ", i + 1);
 			while (!read_buffer(&opt)) {
-				fprintf(stdout, "Número invalido! Tiene que ser mayor de 1!\n");
-				fprintf(stdout, "Elegir elemento %lli: ", i + 1);
+				fprintf(stdout, "Número invalido! Tiene que ser mayor de -2147483649 y menor de 2147483648!\n");
+				fprintf(stdout, "Elegir elemento %d: ", i + 1);
 			}
 			unordered_array[i] = opt;
 		}
 		else {
-			unordered_array[i] = gen_rand((n * 10) * -1, n * 10);
+			unordered_array[i] = gen_rand(-100000000, 100000000);
 		}
 	}
 
 	if (merge) {
-		// merge sort
+		fprintf(stdout, "Merge sort corriendo... ");
+		fflush(stdout);
+		memcpy(work_array, unordered_array, sizeof(int) * n);
+		start_timer();
+		merge_sort(work_array, n);
+		stop_timer();
+		fprintf(stdout, "done\n");
+		print_timer();
 	}
 
 	if (quick) {
diff --git a/test/Makefile b/test/Makefile
index 8a6beb5..c99423b 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -2,7 +2,8 @@ CC=gcc
 CFLAGS=-Wall -I../src/include -DDEBUG -g
 SRC=test.c
 OBJ=$(SRC:.c=.o)
-OBJ+=../src/random.o ../src/bubble_sort.o ../src/timer.o ../src/count_sort.o ../src/quick_sort.o ../src/bitonic_sort.o ../src/selection_sort.o
+
+OBJ+=../src/random.o ../src/bubble_sort.o ../src/timer.o ../src/count_sort.o ../src/quick_sort.o ../src/merge_sort.o ../src/bitonic_sort.o ../src/selection_sort.o
 
 all: test
 
diff --git a/test/test.c b/test/test.c
index 3f44655..854662d 100644
--- a/test/test.c
+++ b/test/test.c
@@ -20,9 +20,10 @@
 #include "random.h"
 #include "bubble_sort.h"
 #include "count_sort.h"
-#include "quick_sort.h"
-#include "bitonic_sort.h"
 #include "selection_sort.h"
+#include "bitonic_sort.h"
+#include "merge_sort.h"
+#include "quick_sort.h"
 
 static int *test_case;
 static int *test_array;
@@ -51,7 +52,7 @@ void cleanup() {
  * El programa de test
  */
 int main(int argc, char **argv) {
-	int n = 65536;
+	int n = 32768;
 	int i;
 	int gen;
 	int pass;
@@ -59,8 +60,20 @@ int main(int argc, char **argv) {
 	int failed = 0;
 
 	test_case = malloc(sizeof(int) * n);
+	if (test_case == NULL) {
+		fprintf(stderr, "Error: Out of heap space!\n");
+		exit(1);
+	}
 	qarray = malloc(sizeof(int) * n);
+	if (qarray == NULL) {
+		fprintf(stderr, "Error: Out of heap space!\n");
+		exit(1);
+	}
 	test_array = malloc(sizeof(int) * n);
+	if (test_array == NULL) {
+		fprintf(stderr, "Error: Out of heap space!\n");
+		exit(1);
+	}
 
 	atexit(cleanup);
 
@@ -148,7 +161,7 @@ int main(int argc, char **argv) {
 		passed++;
 	}
 
- 	//test bitonic
+	 // Test bitonic sort
 	pass = 1;
 	memcpy(test_array, test_case, sizeof(int) * n);
 	fprintf(stdout, "\tbitonic sort: ");
@@ -167,7 +180,7 @@ int main(int argc, char **argv) {
 		passed++;
 	}
 
-		// Test selection sort
+	// Test selection sort
 	pass = 1;
 	memcpy(test_array, test_case, sizeof(int) * n);
 	fprintf(stdout, "\tselection sort: ");
@@ -186,6 +199,25 @@ int main(int argc, char **argv) {
 		passed++;
 	}
 
+	// Test merge sort
+	pass = 1;
+	memcpy(test_array, test_case, sizeof(int) * n);
+	fprintf(stdout, "\tmerge sort: ");
+	fflush(stdout);
+	merge_sort(test_array, n);
+	for (i = 0; i < n; i++) {
+		if (test_array[i] != qarray[i]) {
+			fprintf(stdout, "fail\n");
+			failed++;
+			pass = 0;
+			break;
+		}
+	}
+	if (pass) {
+		fprintf(stdout, "pass\n");
+		passed++;
+	}
+
 	fprintf(stdout, "%d tests passed\n", passed);
 	fprintf(stdout, "%d tests failed\n", failed);