diff --git a/du1/program.c b/du1/program.c
index afc9a96..721090f 100644
--- a/du1/program.c
+++ b/du1/program.c
@@ -11,6 +11,10 @@ int main() {
     for (int i = 0; i < VELKOST_POLA; ++i) {
         int value = 0;
         int r = scanf("%d", &value);
+	 if(i == 0 && value < 0) {
+            printf("Chyba: Málo platných hodnôt.\n");
+            return 1;
+        }
         if(r > 0 && value > 0) {
             pole[i] = value;
             participant_count++;