Two colors

Write a program that, given an undirected graph, tells if we can paint all vertices with only two colors, in such a way that no two neighboring vertices have the same color.

Input

Input consists of several cases, each with the number of vertices $n$ and the number of edges $m$ , followed by $m$ pairs $x$ $y$ indicating an edge between $x$ and $y$ . Suppose $1 \le n \le 10^4$ , $0 \le m \le 5n$ , that vertices are numbered from 0 to $n - 1$ , $x \ne y$ , and that there is no more than one edge between any pair $x$ $y$ .

Output

For every case, print “yes” if the graph is two-colorable, and “no” otherwise.

Problem information

Author: Unknown
Translator: Salvador Roura

Generation: 2026-01-25T10:36:55.210Z