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