#174 I Want to Cycle.

Statement

Statement language

You are given a directed simple graph with $N$ vertices and $M$ edges.

We say that a vertex $v$ can visit a cycle if, starting from $v$ and moving along directed edges, it is possible to reach a vertex that belongs to some directed cycle.

Find the number of vertices from which no cycle can be visited.

Input

The input is given in the following format.

$N\ M$ $u_1\ v_1$ $u_{}$

Output

Print the number of vertices from which no cycle can be visited.

Constraints

$1 \le N \le 100\,000$ .
$0 \le M \le 100\,000$ .
$1 \leq_{}$ ().

Subtasks

#	Score	Constraints
1	100	The full constraints apply.

Samples

Sample 1

Input

Output

4

There is no cycle in the graph, so no vertex can visit a cycle.

Sample 2

Input

Output

2

Vertices $2$ and $3$ are contained in a cycle. From vertices $1$ and $4$ , this cycle can be visited.

From vertices $5$ and , no cycle can be visited, so the answer is .