i don't know how to solve this problem even after i read the editorial, i just understand the bfs part https://codeforces.me/problemset/problem/1037/D

is it worth it to study this book to improve CP,math for ACM-ICPC and to decrease solving rate for some time ?

what is the benefit of this book ?who used it

i'm searching for competitive dudes who are serious about training and regularly participating in contests i know that i'm unrated but for every master one day was a starter ... so please inform me in the comments(facebook e-mail or send privately) if u would like to join a small Facebook group for training .

UPD: i don't know why u guys are downvoting me that's very rude of u... i just don't want to train alone is there a problem ?

UPD2: we are looking for people whose rank is expert because we have some in the group but not many if your rank is an expert or high specialist please send me privately