- Time limit: 1.00 s
- Memory limit: 512 MB
Given an undirected graph, your task is to determine its girth, i.e., the length of its shortest cycle.
The first input line has two integers n and m: the number of nodes and edges. The nodes are numbered 1,2,\dots,n.
After this, there are m lines describing the edges. Each line has two integers a and b: there is an edge between nodes a and b.
You may assume that there is at most one edge between each two nodes.
Print one integer: the girth of the graph. If there are no cycles, print -1.
- 1 \le n \le 2500
- 1 \le m \le 5000
5 6 1 2 1 3 2 4 2 5 3 4 4 5