Cliques

Given an undirected graph with $n$ vertices and $m$ edges, tell whether every connected component is a clique, that is, if all the vertices of the component are directly connected to each other.

Input

Input consists of several cases. Each case begins with $n$ and $m$ , followed by $m$ pairs $x$ $y$ , with $x \ne y$ , indicating an edge between $x$ and $y$ . Suppose $1 \le n \le 10^5$ , $0 \le m \le 5n$ , that the vertices are numbered between 0 and $n-1$ , and that there are no repeated edges.

Output

For each given graph, print “SI” if every connected component is a clique, and “NO” otherwise.

Observation

Even if a green light is obtained, only solutions that perform a single graph traversal will receive the maximum score.

Problem information

Author: Unknown
Translator: Salvador Roura

Generation: 2026-01-25T23:06:42.008Z