I entered Educational Codeforces Round 48, and I got WA in problem E.

With the contest end, I checked command : wrong answer 154th numbers differ — expected: '0.0000000', found: '-0.0000000', error = '-0.0000000'

I tried change -0 to 0 with abs function, but it doesn't work.

My source code : http://mirror.codeforces.com/contest/1016/submission/41186743

Why this happens, and how can I fix it? Does it have a meaning that I do not know at -0.000?

http://mirror.codeforces.com/contest/913/submission/34021734 Accepted

http://mirror.codeforces.com/contest/913/submission/34049526 Wrong answer on test 4

http://mirror.codeforces.com/contest/913/submission/34049558 Accepted

What is diffrent ? I edit just one line about ll b in dfs function..