#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(ll i=0;i<n;i++)
#define repl(i,l,r) for(ll i=(l);i<(r);i++)
#define per(i,n) for(ll i=(n)-1;i>=0;i--)
#define perl(i,r,l) for(ll i=r-1;i>=l;i--)
#define fi first
#define se second
#define pb push_back
#define ins insert
#define pqueue(x) priority_queue<x,vector<x>,greater<x>>
#define all(x) (x).begin(),(x).end()
#define CST(x) cout<<fixed<<setprecision(x)
#define vtpl(x,y,z) vector<tuple<x,y,z>>
#define rev(x) reverse(x);
using ll=long long;
using vl=vector<ll>;
using vvl=vector<vector<ll>>;
using pl=pair<ll,ll>;
using vpl=vector<pl>;
using vvpl=vector<vpl>;
const ll MOD=1000000007;
const ll MOD9=998244353;
const int inf=1e9+10;
const ll INF=4e18;
const ll dy[9]={0,1,-1,0,1,1,-1,-1,0};
const ll dx[9]={1,0,0,-1,1,-1,1,-1,0};
template<class T> inline bool chmin(T& a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
template<class T> inline bool chmax(T& a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}

struct UnionFind {
    vector<int> par;
    vector<int> edge;
    
    UnionFind(int n) : par(n, -1),edge(n, 0) {}

    int root(int x) {
        if (par[x] < 0) return x;
        else return par[x] = root(par[x]);
    }
    
    bool same(int x, int y) {
        return root(x) == root(y);
    }
    
    bool merge(int x, int y) {
        x = root(x); y = root(y);
        if (x == y) {
            edge[x]++;
            return false;
        }
        if (par[x] > par[y]) swap(x, y);
        par[x] += par[y];
        par[y] = x;
        edge[x] += edge[y]+1;
        return true;
    }
    
    int size(int x) {
        return -par[root(x)];
    }
};
vl topsort(vvl &g){
    ll n=g.size();
    vl ans,ind(n);
    rep(i,n)for(auto e:g[i])ind[e]++;
    queue<ll> que;
    rep(i,n)if(!ind[i])que.push(i);
    while(!que.empty()){
        ll v=que.front();que.pop();
        ans.pb(v);
        for(auto nv:g[v]){
            ind[nv]--;if(!ind[nv])que.push(nv);
        }
    }
    return ans;
}

int main(){
    ll n,m;cin >> n >>m;
    vpl edge(m);
    UnionFind uf(n);
    rep(i,m){
        ll a,b;cin >> a >> b;a--;b--;
        edge[i]={a,b};
        uf.merge(a,b);
    }
    vector<vpl> es(n);
    rep(i,m){
        es[uf.root(edge[i].fi)].push_back(edge[i]);
    }
    vpl ans;
    rep(i,n){
        if(es[i].empty())continue;
        vl pls;
        for(auto p:es[i]){
            pls.push_back(p.first);
            pls.push_back(p.se);
        }
        sort(all(pls));
        pls.erase(unique(all(pls)),pls.end());
        ll z=pls.size();
        vvl g(z);
        for(auto p:es[i]){
            ll a=lower_bound(all(pls),p.first)-pls.begin();
            ll b=lower_bound(all(pls),p.second)-pls.begin();
            g[a].push_back(b);
        }
        auto tps=topsort(g);
        if(tps.size()!=z){
            rep(j,z)ans.push_back({pls[j],pls[(j+1)%z]});
        }
        else{
            rep(j,z-1){
                ans.push_back({pls[tps[j]],pls[tps[j+1]]});
            }
        }
    }
    cout << ans.size() <<endl;
    for(auto p:ans)cout << p.fi+1 <<" " << p.se+1 <<endl;
}