#include <algorithm>

 #include <cstdio>

 #include <map>

 using namespace std;

 const int N();

 map<int,bool>Map[N];

 int n,m,v,u;

 int edgesum,head[N];

 int edgesum2,head2[N];

 struct Edge

 {

     int from,to,next;

     Edge(int from=,int to=,int next=) :

         from(from),to(to),next(next) {}

 }edge[N],edge2[N];

 int ins(int from,int to)

 {

     edge[++edgesum]=Edge(from,to,head[from]);

     return head[from]=edgesum;

 }

 int ins2(int from,int to)

 {

     edge2[++edgesum2]=Edge(from,to,head2[from]);

     return head2[from]=edgesum2;

 }

 int dfn[N],tim,low[N],vis[N];

 int Stack[N],top,instack[N];

 int col[N],colsum;

 void DFS(int now)

 {

     dfn[now]=low[now]=++tim; vis[now]=;

     Stack[++top]=now; instack[now]=;

     for(int i=head[now];i;i=edge[i].next)

     {

         int to=edge[i].to;

         if(instack[to]) low[i]=min(low[i],dfn[to]);

         else if(!vis[to])

                 DFS(to),low[i]=min(low[i],low[to]);

     }

     if(low[now]==dfn[now])

     {

         colsum++;

         col[now]=colsum;

         for(;Stack[top]!=now;top--)

         {

             col[Stack[top]]=colsum;

             instack[Stack[top]]=;

         }

         instack[now]=;

         top--;

     }

 }

 int main()

 {

     scanf("%d%d",&n,&m);

     for(;m--;)

     {

         scanf("%d%d",&u,&v);

         ins(u,v);

     }

     for(int i=;i<=n;i++)

         if(!vis[i]) DFS(i);

     for(int i=;i<=n;i++)

       for(int u=head[i];u;u=edge[i].next)

       {

           int v=edge[i].to;

             if(col[i]!=col[v])

                 if(Map[col[i]].find(col[v])==Map[col[i]].end())

                 {

                     Map[col[i]][col[v]]=;

                     ins2(col[i],col[v]);

             }

       }

     return ;

 }