diff --git a/du1/program.c b/du1/program.c
index d1c8f85..009295a 100644
--- a/du1/program.c
+++ b/du1/program.c
@@ -13,6 +13,10 @@ int main() {
         int r = scanf("%d", &results[i]);
         if (r == 1) {
             if (results[i] < 0) {
+                if (i == 0) {
+                    printf("Chyba: Málo platných hodnôt.\n");
+                    return 0;
+                }
                 break;
             }
             value_count++;