question
https://codeforces.me/contest/1400/problem/E is same as https://www.spoj.com/problems/NPC2014B/ with same constraints
Duplicate question in Educational Codeforces Round 94 (Rated for Div. 2)
question
https://codeforces.me/contest/1400/problem/E is same as https://www.spoj.com/problems/NPC2014B/ with same constraints