#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
#include <fstream>
#include <utility>
#include <functional>
#include <time.h>
#include <stack>
#include <array>
#include <list>
#include <atcoder/all>
#define popcount __builtin_popcount
using namespace std;
using namespace atcoder;
typedef long long ll;
typedef pair<int, int> P;
struct SCC{
    vector<vector<int>> g, gr;
    int n, k;
    vector<int> cmp, vs;
    vector<bool> used;
    void dfs(int x){
        used[x]=1;
        for(auto y:g[x]){
            if(!used[y]) dfs(y);
        }
        vs.push_back(x);
    }
    void rdfs(int v, int k){
        used[v]=1;
        cmp[v]=k;
        for(auto y:gr[v]){
            if(!used[y]) rdfs(y, k);
        }
    }
    SCC(const vector<vector<int>> &g):g(g), n(g.size()), cmp(n), used(n){
        gr.resize(n);
        for(int x=0; x<n; x++) for(auto y:g[x]) gr[y].push_back(x);
        for(int i=0; i<n; i++){
            if(!used[i]) dfs(i);
        }
        fill(used.begin(), used.end(), 0);
        k=0;
        for(int i=vs.size()-1; i>=0; i--){
            if(!used[vs[i]]) rdfs(vs[i], k++);
        }
    }
};
int main()
{
    int n, m;
    cin>>n>>m;
    vector<vector<int>> g(n), g1(n);
    for(int i=0; i<m; i++){
        int u, v;
        cin>>u>>v;
        u--; v--;
        g[u].push_back(v);
        g1[u].push_back(v);
        g1[v].push_back(u);
    }
    SCC scc(g);
    vector<int> w;
    bool used[200020]={};
    auto dfs=[&](auto dfs, int x)->void{
        used[x]=1;
        w.push_back(x);
        for(auto y:g1[x]){
            if(used[y]) continue;
            dfs(dfs, y);
        }
    };
    vector<P> ans;
    for(int i=0; i<n; i++){
        if(used[i]) continue;
        w.clear();
        dfs(dfs, i);
        map<int, int> mp;
        for(auto x:w){
            mp[scc.cmp[x]]++;
        }
        bool myon=0;
        for(auto p:mp){
            if(p.second!=1){
                myon=1;
            }
        }
        if(myon){
            for(int j=0; j<(int)w.size()-1; j++){
                ans.push_back({w[j], w[j+1]});
            }
            ans.push_back({w.back(), w[0]});
        }else{
            sort(w.begin(), w.end(), [&](int x, int y){ return scc.cmp[x]<scc.cmp[y];});
            for(int j=0; j<(int)w.size()-1; j++){
                ans.push_back({w[j], w[j+1]});
            }
        }
    }
    cout<<ans.size()<<endl;
    for(auto p:ans){
        cout<<p.first+1<<" "<<p.second+1<<endl;
    }
    return 0;
}