http://www.spoj.com/problems/MUSKET/ hello everyone,there is a nice problem from polish olympiad,i have tried to solve it but ... can someone explain how solve it? or if have some ideas share it each other. sorry for my bad english.

I write virtual contest-Round 141 and find this interesting problem. http://codeforces.me/contest/228/problem/C

can someone explain it a bit more and gives me clear implementation,in editorial there is no comments and a few people have solved it.thanks

i am trying to solve http://www.spoj.com/problems/NUMTSN/ this problem on spoj. can someone who has solved this problem give me some advice why my code gives me wa. https://ideone.com/Ycnepw