A10381 | TOF

The first line of the input contains two integers $n$ and $m$ ( $1<=n,m<=5000$ ) — the number of vertices and then number of directed edges in the input graph.

Each of the next $m$ lines contains a pair of integers $u_{i}$ and $v_{i}$ ( $1<=u_{i},v_{i}<=n$ ), meaning there is a directed  edge in the input graph.

You may assume that the graph won't contain any self-loops and there is at most one edge between any unordered pair of vertices.

Print a single integer — the minimum possible number of dfs calls that can be achieved with permuting the edges.

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