Hello friends, i appeared in codeforces round 433DIV2. My solution for problem DIV2C passed the pretests but didn't pass the system test. Because there was a bug in the line 65 & 66 because i had erased the iterator and then tried to use the value stored at it(i just replaced line 65 & 66 with each other, then solution got accepted). So, it shouldn't have passed pretests even. but still it passed . Can someone explain me this abnormal behaviour of iterator.