#include<cstdio>
#include<cmath>
#include<algorithm>
#include<set>
#include<map>
#include<cstring>
#include<string>
#include<vector>
#include<queue>
#include<iomanip>
#include<iostream>
#include<stack>
using namespace std;

#define inf 0x3f3f3f3f
const int N = 1e2+10;
const int M = 1e4+10;

//与边相关
struct edgeK
{
    int u, v, next, w;
} eK[M];
int pK[N], eidK;
inline void InitEdgeK()
{
    memset(pK, -1, sizeof(pK));
    eidK = 0;
}
inline void InsertK(int u, int v, int w = 0)
{
    eK[eidK].next = pK[u];
    eK[eidK].u = u;
    eK[eidK].v = v;
    eK[eidK].w = w;
    pK[u] = eidK++;
}
//强连通分量
int timeStamp = 0;
int dfn[N], low[N];
int sccCnt = 0;//强连通分量的数量
int sccId[N];//记录每个点属于的强连通分量的编号
set<int> scc[N];
stack<int> sBcc;
void DfsScc(int u)
{
    dfn[u] = low[u] = ++timeStamp;
    sBcc.push(u);
    for(int i = pK[u]; i != -1; i = eK[i].next)
    {
        int v = eK[i].v;
        if(dfn[v] == 0)//没有被访问过
        {
            DfsScc(v);
            low[u] = min(low[u], low[v]);
        }
        //在别人的强连通分量里面
        else if(!sccId[v])//对于已经求出scc的点，直接
        {
            low[u] = min(low[u], dfn[v]);
        }
    }
    //一个点是一个强连通分量里面最先发现的点（此时他的子节点已经访问好了），就把此强连通分量存好
    if(low[u] == dfn[u])
    {
        ++sccCnt;
        while(true)
        {
            int x = sBcc.top();
            sBcc.pop();
            sccId[x] = sccCnt;
            scc[sccCnt].insert(x);
            if(x == u)
                break;
        }
    }
}
//缩点
struct edge
{
    int v, next, w;
} e[M];
int p[N], eid;
inline void InitEdge()
{
    memset(p, -1, sizeof(p));
    eid = 0;
}
inline void Insert(int u, int v, int w = 0)
{
    e[eid].next = p[u];
    e[eid].v = v;
    e[eid].w = w;
    p[u] = eid++;
}
int main()
{
    //freopen("in.txt","r", stdin);
    //freopen("out.txt","w", stdout);
    ios::sync_with_stdio(false);
    InitEdgeK();
    int n, m;
    cin >> n >> m;
    for (int i = 0; i < m; ++i)
    {
        int u, v;
        cin >> u >> v;
        InsertK(u, v);
    }
    memset(dfn, 0, sizeof(dfn));
    memset(sccId, 0, sizeof(sccId));
    timeStamp = sccCnt = 0;
    //有向图不能保证访问到每一个点
    for(int i = 1; i <= n; i++)
    {
        if(!dfn[i])
            DfsScc(1);
    }
    InitEdge();
    for(int u = 1; u <= n; ++u) {
        for(int i = p[u]; i != -1; i = e[i].next) {
            int v = e[i].v;
            if(sccId[u] != sccId[v]) {
                Insert(sccId[u], sccId[v]);
            }
        }
    }
    return 0;
}