diff --git a/cv5/a_train.c b/cv5/a_train.c
index dbc539e..8bb0856 100644
--- a/cv5/a_train.c
+++ b/cv5/a_train.c
@@ -22,7 +22,7 @@ struct car* add_car(struct car* first,const char* target) {
 void print_train(struct car* first) {
     struct car* this = first;
     if(first == NULL){
-        return;   
+        exit(0);   
     }
     else{
         while(this != NULL){
@@ -35,7 +35,7 @@ void print_train(struct car* first) {
 
 void cancel_train(struct car* first) {
     if(first == NULL){
-        return;
+        exit(0);
     }
     cancel_train(first->next);
     free(first);