diff --git a/main.c b/main.c
index 63568ee..f5e8101 100644
--- a/main.c
+++ b/main.c
@@ -63,6 +63,7 @@ int main() {
         while (1) {
                 unsigned char input = getchar();
                 if (input == '\n') break;
+                if (input >= 'a' && input <= 'z') input -= 32;
                 last_char = input;
 
                 if (input < '0' || input > '9') continue;