Yesterday 's contest had some very good problems , unfortunately, it became unrated.

Problem Link :Problem - C - Codeforces

The problem is based on standard topological sort Prerequisite problem .

I am stuck somewhere .

If the cycle was found in the graph I printed -1 as the answer.

else

I found the topical sort of all the chapters , using cycle detection + DFS + queue.

**After finding the topological ordering (stored in a queue) of chapters how do I count the number of times** I will have to read the book/number of passes required???

Please help !!!