diff --git a/cv8/program.c b/cv8/program.c
index 835536a..c34ee26 100644
--- a/cv8/program.c
+++ b/cv8/program.c
@@ -59,6 +59,10 @@ void ask(struct node* tree){
     }
     char buff[SIZE];
     char* r = fgets(buff, SIZE, stdin);
+    if(r == NULL){
+        puts("Koniec vstupu");
+        return;
+    }
     r = fgets(buff, SIZE, stdin);
     if(r[0] == 'a' && tree->left != NULL){
         tree = tree->left;