Transitivity of a graph#3988
Undirected graph without loops and multiple edges is called transitive, if vertices and are connected with an edge, vertices and are connected with an edge, and all three vertices , , and are different, then vertices and must also be connected with an edge.
Verify that a given undirected graph is transitive.
The first line contains the number of vertices and edges m~(3 \le n \le 100, 0 \le m \le (n \cdot (n - 1)) / 2) of the graph. Then lines are given - the list of edges.
Print "YES" or "NO" — the answer to the question about transitivity of a graph.
Example 1
Example 2