//By SiriusRen#include <queue>#include <cstdio>#include <cstring>#include <algorithm>using namespace std;const int N=200050;int n,m,xx,yy,v[N],next[N],first[N],tot,f[N],in[N],out[N],ans;void add(int x,int y){v[tot]=y,next[tot]=first[x],first[x]=tot++;}queue<int>q;int main(){    memset(first,-1,sizeof(first));    scanf("%d%d",&n,&m);    for(int i=1;i<=m;i++){        scanf("%d%d",&xx,&yy);        add(xx,yy);in[yy]++,out[xx]++;    }    for(int i=1;i<=n;i++)if(!in[i])q.push(i),f[i]=1;    while(!q.empty()){        int t=q.front();q.pop();        for(int i=first[t];~i;i=next[i]){            in[v[i]]--,f[v[i]]+=f[t];            if(!in[v[i]])if(out[v[i]])q.push(v[i]);else ans+=f[v[i]];        }    }    printf("%d\n",ans);}