Hello codeforces.

272176008 this submission is wrong but got accepted.

1 
4 5
3 3 4 4

in this test correct answer is 4 but output is 5

MikeMirzayanov please add this test.

I need help to reach expert. Can you tell me what algorithms, data structures should I learn?. Please help me to reach expert.

Sorry for my poor english.

Yesterday I saw my rating is 1501. And today i visit to codeforces and i saw my rating is 1493. I checked other people's rating and they are also decreased. Why?