#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for(int i = 0; i < n; i++)
#define rep2(i, x, n) for(int i = x; i <= n; i++)
#define rep3(i, x, n) for(int i = x; i >= n; i--)
#define each(e, v) for(auto &e: v)
#define pb push_back
#define eb emplace_back
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define sz(x) (int)x.size()
using ll = long long;
using pii = pair<int, int>;
using pil = pair<int, ll>;
using pli = pair<ll, int>;
using pll = pair<ll, ll>;
const int MOD = 1000000007;
//const int MOD = 998244353;
const int inf = (1<<30)-1;
const ll INF = (1LL<<60)-1;
template<typename T> bool chmax(T &x, const T &y) {return (x < y)? (x = y, true) : false;};
template<typename T> bool chmin(T &x, const T &y) {return (x > y)? (x = y, true) : false;};

struct io_setup{
    io_setup(){
        ios_base::sync_with_stdio(false);
        cin.tie(NULL);
        cout << fixed << setprecision(15);
    }
} io_setup;

struct Union_Find_Tree{
    vector<int> data;
    const int n;
    
    Union_Find_Tree(int n) : data(n, -1), n(n) {}
    
    int root(int x){
        if(data[x] < 0) return x;
        return data[x] = root(data[x]);
    }

    int operator [] (int i) {return root(i);}
    
    bool unite(int x, int y){
        x = root(x), y = root(y);
        if(x == y) return false;
        if(data[x] > data[y]) swap(x, y);
        data[x] += data[y], data[y] = x;
        return true;
    }
    
    int size(int x) {return -data[root(x)];}
    
    bool same(int x, int y) {return root(x) == root(y);}
    
    void clear() {fill(begin(data), end(data), -1);}
};

vector<int> par;
vector<pii> ans;

template<bool directed = true>
struct Graph{
    struct edge{
        int to, id;
        edge(int to, int id) : to(to), id(id) {}
    };

    vector<vector<edge>> es;
    const int n;
    int m;
    vector<int> depth, deg;

    Graph(int n) : es(n), n(n), m(0), depth(n, 0), deg(n, 0) {}

    void add_edge(int from, int to){
        es[from].emplace_back(to, m);
        if(!directed) es[to].emplace_back(from, m);
        deg[to]++;
        m++;
    }

    void solve(){
        Union_Find_Tree uf(n);
        rep(i, n){
            each(e, es[i]) uf.unite(i, e.to);
        }
        vector<vector<int>> ids(n);
        rep(i, n){
            ids[uf[i]].eb(i);
        }

        rep(t, n){
            queue<int> que;
            each(i, ids[t]){
                if(deg[i] == 0) que.emplace(i);
            }
            int K = sz(ids[t]);
            vector<vector<int>> layer(K+1);

            while(!empty(que)){
                int i = que.front(); que.pop();
                layer[depth[i]].eb(i);
                each(e, es[i]){
                    chmax(depth[e.to], depth[i]+1);
                    if(--deg[e.to] == 0) que.emplace(e.to);
                }
            }

            rep3(i, K-1, 0){
                rep(j, sz(layer[i])-1){
                    ans.eb(par[layer[i][j]], par[layer[i][j+1]]);
                }
                if(!empty(layer[i+1])){
                    ans.eb(par[layer[i].back()], par[layer[i+1].front()]);
                }
            }
        }
    }
};

template<bool directed = true>
struct Strongly_Connected_Components{
    struct edge{
        int to, id;
        edge(int to, int id) : to(to), id(id) {}
    };

    vector<vector<edge>> es, rs;
    vector<int> vs, comp;
    vector<bool> used;
    const int n;
    int m;

    Strongly_Connected_Components(int n) : es(n), rs(n), vs(n), comp(n), used(n), n(n), m(0) {}

    void add_edge(int from, int to){
        es[from].emplace_back(to, m), rs[to].emplace_back(from, m);
        if(!directed) es[to].emplace_back(from, m), rs[from].emplace_back(to, m);
        m++;
    }

    void _dfs(int now){
        used[now] = true;
        for(auto &e: es[now]){
            if(!used[e.to]) _dfs(e.to);
        }
        vs.push_back(now);
    }

    void _rdfs(int now, int cnt){
        used[now] = true, comp[now] = cnt;
        for(auto &e: rs[now]){
            if(!used[e.to]) _rdfs(e.to, cnt);
        }
    }

    Graph<true> decompose(){
        fill(begin(used), end(used), false);
        for(int i = 0; i < n; i++){
            if(!used[i]) _dfs(i);
        }
        fill(begin(used), end(used), false), reverse(begin(vs), end(vs));
        int cnt = 0;
        for(auto &e: vs){
            if(!used[e]) _rdfs(e, cnt++);
        }
        Graph<true> G(cnt);
        for(int i = 0; i < n; i++){
            for(auto &e: es[i]){
                int u = comp[i], v = comp[e.to];
                if(u != v) G.add_edge(u, v);
            }
        }
        return G;
    }

    int operator [] (int k) const {return comp[k];}
};

int main(){
    int N, M; cin >> N >> M;

    Strongly_Connected_Components<true> scc(N);
    Union_Find_Tree uf(N);

    rep(i, M){
        int u, v; cin >> u >> v; u--, v--;
        scc.add_edge(u, v);
        uf.unite(u, v);
    }

    Graph<true> G = scc.decompose();

    vector<vector<int>> ids(N);
    rep(i, N) ids[scc.comp[i]].eb(i);
    par.assign(N, -1);

    rep(i, N){
        if(sz(ids[i]) >= 2){
            rep(j, sz(ids[i])){
                ans.eb(ids[i][j], ids[i][(j+1)%sz(ids[i])]);
            }
        }
        if(sz(ids[i]) > 0){
            par[i] = ids[i][0];
        }
    }

    if(G.n != N){
        cout << N << '\n';
        rep(i, N) cout << i+1 << ' ' << (i+1)%N+1 << '\n';
        return 0;
    }

    //G.solve();

    rep(i, N-1){
        if(empty(ids[i]) || empty(ids[i+1])) continue;
        if(uf.same(ids[i][0], ids[i+1][0])){
            ans.eb(ids[i][0], ids[i+1][0]);
        }
    }

    cout << sz(ans) << '\n';

    each(e, ans){
        cout << e.first+1 << ' ' << e.second+1 << '\n';
    }
}