#include<bits/stdc++.h>
int n,m,a[1000005],b[1000005],fa[1000005],ans;
std::vector<int> to[1000005],from[1000005];
bool vis[1000005],r[1000005];
void init(int now)
{
    vis[now]=true;
    for(auto i:from[now])
        if(!vis[a[i]])
        {
            fa[a[i]]=now;
            r[i]=true;
            init(a[i]);
        }
}
signed main()
{
    std::ios::sync_with_stdio(false);
    std::cin>>n>>m;
    for(int i=1;i<=m;++i)
    {
        std::cin>>a[i]>>b[i];
        to[a[i]].push_back(i);
        from[b[i]].push_back(i);
    }
    init(n);
    std::fill(vis+1,vis+1+n,false);
    if(fa[1])
    {
        ++ans;
    }
    std::queue<int> que;
    que.push(1);
    while(!que.empty())
    {
        int now=que.front();
        que.pop();
        for(auto i:to[now])
        {
            if(!vis[b[i]])
                que.push(b[i]),vis[b[i]]=true;
            if(fa[now]==b[i])
                continue;
            if(fa[b[i]])
                ++ans;
        }
    }
    std::cout<<ans<<std::endl;
    return 0;
}