#include<cstdio>
#include<vector>
#include<cstring>
#define NMAX 300
using namespace std;
int n,m,i,nr,k,x,y;
int viz[NMAX],viz1[NMAX],ord[NMAX];
vector<int>v1[NMAX],v[NMAX],cmp[NMAX];
void Dfs(int nod)
{
    vector<int>::iterator it;
    viz[nod]=1;
    for (it=v[nod].begin();it!=v[nod].end();++it)
    {
        if (viz[*it]==0) Dfs(*it);
    }
    ord[++k]=nod;
}
void DFS(int nod)
{
    cmp[nr].push_back(nod);
    viz1[nod]=nr;
    vector<int>::iterator it;
    for (it=v1[nod].begin();it!=v1[nod].end();++it)
    {
        if (viz1[*it]==0) DFS(*it);
    }
}
int main()
{
    freopen("strazi.in","r",stdin);
    freopen("strazi.out","w",stdout);
    scanf("%d%d",&n,&m);
    for (i=1;i<=m;++i)
    {
        scanf("%d%d",&x,&y);
        v[x].push_back(y);
        v1[y].push_back(x);
    }
    for (i=1;i<=n;++i)
        if (viz[i]==0) Dfs(i);
    for (i=n;i>=1;--i)
    {
        if (viz1[ord[i]]==0)
        {
            ++nr;
            DFS(ord[i]);
        }
    }
    printf("%d\n",nr-1);
    for (i=1;i<nr;++i)
        {
            x=cmp[i][cmp[i].size()-1];
            y=cmp[i+1][cmp[i+1].size()-1];
            printf("%d %d\n",x,y);
        }
    for (i=1;i<=nr;++i)
    {
        vector<int>::iterator it;
        for (it=cmp[i].begin();it!=cmp[i].end();++it)
            printf("%d ",*it);
    }
    return 0;
}