> #include<iostream>
> #include<queue>
> #include<cstdio>
> #include<cstring>
> #include<algorithm>
> #define maxn 105
> using namespace std;
> int n,m;
> int ans=0;
> int maz[maxn][maxn];
> void floyd()
> {
>     for(int k=1;k<=n;k++)
>         for(int i=1;i<=n;i++)
>             if(maz[i][k])
>                 for(int j=1;j<=n;j++)
>                 {
>                     if(!maz[k][j]||maz[i][j])
>                         continue;
>                     if(maz[i][k]==1&&maz[k][j]==1)
>                     {
>                         maz[i][j]=1;
>                         maz[j][i]=-1;
>                     }
>                     else if(maz[i][k]==-1&&maz[k][j]==-1)
>                     {
>                         maz[i][j]=-1;
>                         maz[j][i]=1;
>                     }
>                 }
> }
> int main()
> {
>     int i,j,u,v;
>     scanf("%d%d",&n,&m);
>     memset(maz,0,sizeof(maz));
>     for(i=0;i<m;i++)
>     {
>         scanf("%d%d",&u,&v);
>         maz[u][v]=1;
>         maz[v][u]=-1;
>     }    
>     floyd();    
>     ans=0;
>     for(i=1;i<=n;i++)
>     {
>         int sum=0;
>         for(j=1;j<=n;j++)
>             if(maz[i][j])
>                 sum++;
>         if(sum==n-1)
>             ans++;
>     }
>     printf("%d\n",ans);
>     return 0;
> }