LCA

The directed graph is given. How many pairs of vertices $(i,j)$ have the common ancestor? The common ancestor of vertices $i$ and $j$ is a vertex $k$ for which $i$ and $j$ are reachable from $k$.

Input

The first line contains the number of vertices $n(1\le n\le 10^4)$ and number of edges $m(0\le m\le 10^4)$ in a 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 the number of pairs.

Examples