diff --git a/normal_distribution.R b/normal_distribution.R
index b107986..2655ee8 100644
--- a/normal_distribution.R
+++ b/normal_distribution.R
@@ -93,6 +93,30 @@ pnorm_between <- function(dataset = vector(), min = 0, max = 0, word = "") {
 dnorm_plot("out/dnorm_coins.png", sort(data[, 1]), "Coins Normal Distribution", xlab = "Coins")
 dnorm_plot("out/dnorm_time.png", sort(data[, 2]), "Time Normal Distribution", xlab = "Time (s)")
 
-pnorm_less(sort(data[, 1]), 5, "coins")
-pnorm_more(sort(data[, 1]), 5, "coins")
-pnorm_between(sort(data[, 1]), 8, 10, "coins")
+min <- 0
+max <- 13
+while (T) {
+    cat("Minimum number of coins: ")
+    input <- readLines("stdin", n = 1)
+    input <- as.numeric(input)
+    if (!is.na(input) && input >= min && input < max) {
+        min <- input
+        break
+    }
+}
+
+while (T) {
+    cat("Maximum number of coins: ")
+    input <- readLines("stdin", n = 1)
+    input <- as.numeric(input)
+    if (!is.na(input) && input > min && input <= max) {
+        max <- input
+        break
+    }
+}
+
+pnorm_less(sort(data[, 1]), min, "coins")
+pnorm_more(sort(data[, 1]), min, "coins")
+pnorm_less(sort(data[, 1]), max, "coins")
+pnorm_more(sort(data[, 1]), max, "coins")
+pnorm_between(sort(data[, 1]), min, max, "coins")