Description

Given a directed graph with $n$ vertices and $m$ edges, find the number of strongly connected components that contain more than 1 vertex.

Input Format

The first line contains two integers $n$ and $m$.

Lines 2 through $m+1$, each line contains two integers $a$ and $b$, indicating a directed edge from $a$ to $b$.

Output Format

Output a single line containing the number of strongly connected components with more than 1 vertex.

5 4
2 4
3 5
1 2
4 1

1

Hint

Constraints

For all test points, it is guaranteed that $2 \le n \le 10^4$, $2 \le m \le 5 \times 10^4$, $1 \le a, b \le n$.

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