Update du3/program.c

du3/program.c

@@ -27,7 +27,7 @@ void push_stack(struct stack *s, float value) {
 
 float pop_stack(struct stack *s) {
    if (s->size <= 0) {
-      printf("no input\n");
+      printf("not enough operands\n");
       exit(0);
    }
    s->size--;