Problems
Multiedges
Multiedges
A directed graph is given with a list of edges. Check whether it contains multiedges.
Input data
The first line contains number of vertices in a graph n (1 ≤ n ≤ 100) and number of edges m (1 ≤ m ≤ 10000). Each of the next m lines contains pair of integers - the edges of the graph.
Output data
Print YES if graph contains multiedges and NO otherwise.
Examples
Input example #1
3 4 1 2 2 3 1 3 2 1
Output example #1
NO
Input example #2
3 4 1 2 2 3 1 3 2 3
Output example #2
YES