fix stupid problem 2

validity_check.py

@@ -29,5 +29,6 @@ if __name__ == "__main__":
         if i<3 and prev_line[i] != curr_line[i] :
             print('You modify your data !\n')
             exit(1)
-    if(curr_line[4]) !='VU' or (curr_line[4]) !=' VU' or (curr_line[4]) !='VU ':
+    if(curr_line[3]) !='VU' or (curr_line[3]) !=' VU' or (curr_line[3]) !='VU ':
         print('You have to write "VU" in the last column !\n')
+        exit(1)