move prompt + help

src/util.c

@@ -0,0 +1,14 @@
+#include "util.h"
+#include <stdio.h>
+
+void clear_stdin() {
+    while (getchar() != '\n');
+}
+
+bool is_int_in_range(int x, int start, int end) {
+    if (start <= x && x <= end) {
+        return true;
+    } else {
+        return false;
+    }
+}