Editorial for COCI '08 Contest 5 #3 Jagoda

Remember to use this editorial only when stuck, and not to copy-paste code from it. Please be respectful to the problem author and editorialist.
Submitting an official solution before solving the problem yourself is a bannable offence.

Simulating the process in the task is efficient enough as long as each of the $M$ ~M~ steps is implemented in $\mathcal O(\sqrt N)$ ~\mathcal O(\sqrt N)~, which is easy to achieve.