Problem: We have N boxes, numbered 1 through N. At first, box 1 contains one red ball, and each of the other boxes contains one white ball.

Snuke will perform the following M operations, one by one. In the i-th operation, he randomly picks one ball from box x_i, then he puts it into box y_i.

Find the number of boxes that may contain the red ball after all operations are performed.

Constraints

* 2≤N≤10^5
* 1≤M≤10^5
* 1≤x_i,y_i≤N
* x_i≠y_i
* Just before the i-th operation is performed, box x_i contains at least 1 ball.

Input

The input is given from Standard Input in the following format:


N M
x_1 y_1
:
x_M y_M


Output

Print the number of boxes that may contain the red ball after all operations are performed.

Examples

Input

3 2
1 2
2 3


Output

2


Input

3 3
1 2
2 3
2 3


Output

1


Input

4 4
1 2
2 3
4 1
3 4


Output

3

Solution (in CPP):

Solution:
#include<bits/stdc++.h>
using namespace std;
int n,m,z[100010],b[100010];
int main()
{
    cin>>n>>m;
    b[1]=1;
    for(int i=1;i<=n;++i)z[i]=1;
    for(int i=1;i<=m;++i){
        int x,y;
        scanf("%d%d",&x,&y);
        b[y]|=b[x];
        z[x]--;z[y]++;
        if (z[x]==0)b[x]=0;
	}
	int ans=0;
	for(int i=1;i<=n;++i){
	    if(b[i]&&z[i])ans++;
	}
	cout<<ans<<endl;
}