[solution with settings- gnu c++17] [solution with settings-gnu c++14]

I have never used gnu c++17 as my setting, always c++14. But what actually happened was, in my ide, visual studio, test case-2 gave correct output=13...but on codeforces results of the test was showing output=11 wrong ans. i thought this is some codeforces glitch, i changed the code variables a bit to be able to submit the same code again. But nothing changed. Then i randomly thought of changing lang to c++ 17...and it gave all correct outputs->accepted i.e.

I dont what i should do...its been an year, never used c++17 settings... why did this happen today?