Graph Maximum Matching

An undirected graph has $N$ vertices and $M$ edges.

Write a program that decides whether you can delete some of the edges so that every vertex has degree exactly $1$.

The first line contains $N$ and $M$. ($2 \le N \le 100$, $1 \le M \le 100$)

Each of the next $M$ lines describes one edge and contains the numbers of the two vertices it joins.

Two vertices can be joined by more than one edge. There are no loops. Vertex numbers run from $1$ to $N$.

Print $1$ if deleting some edges can make every vertex have degree $1$, and $0$ otherwise.