diff --git a/du3/program.c b/du3/program.c
index b362777..afdc464 100644
--- a/du3/program.c
+++ b/du3/program.c
@@ -53,6 +53,7 @@ int check(char* input) {
                    }else{resultat=number1/number2;}
             break;
             default:
+            return 0;
               }
        }
        if (resultat-givenResult ==0 ) {