LCA

Input

The first line contains integers $n$ and m~(1 \le n \le 10^4, 0 \le m \le 10^4) — the number of vertices and edges in the graph. Each of the next $m$ lines contains two numbers from $1$ to $n$. The pair $(a,b)$ means that an edge goes from $a$ to $b$.

Output

Print one number — the number of pairs.

Esempi