#include<algorithm>

#include<cstring>

#include<iostream>

#include<cstdio>

#include<queue>

using namespace std;

typedef long long ll;

const int N=1e5+;

int n,m,tot;

int ru[N],head[N],chu[N];

ll dp[N];

queue <int> q;

struct EDGE

{

    int to,nxt;

}edge[N<<];

inline int read()

{

    char ch=getchar();

    int s=,f=;

    while (ch<''||ch>'') {if (ch=='-') f=-;ch=getchar();}

    while (ch>=''&&ch<='') {s=(s<<)+(s<<)+ch-'';ch=getchar();}

    return s*f;

}

void add(int u,int v)

{

    edge[++tot]=(EDGE){v,head[u]};

    head[u]=tot;

}

int dfs(int x)

{

    if (!chu[x])

    {

        dp[x]=;return dp[x];

    }

    for (int i=head[x];i;i=edge[i].nxt)

    {

        int y=edge[i].to;

        if (!dp[y]) dp[y]=dfs(y);

        dp[x]+=dp[y];

    }

    return dp[x];

}

int main()

{

    n=read();m=read();

    for (int i=,u,v;i<=m;i++)

    {

        u=read();v=read();

        add(u,v);chu[u]++;ru[v]++;

    }

    for (int i=;i<=n;i++) if (!dp[i]) dfs(i);

    ll ans=;

    for (int i=;i<=n;i++) if (!ru[i]&&head[i]) ans+=dp[i];//head[i]不可以去掉，生产者没人吃也不是食物链

    printf("%lld\n",ans);

    return ;

}