#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef pair<ld, ld> pd;

typedef vector<int> vi;
typedef vector<ld> vd;
typedef vector<ll> vl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;

#define FOR(i, a, b) for (int i = a; i < (b); i++)
#define F0R(i, a) for (int i = 0; i < (a); i++)
#define FORd(i, a, b) for (int i = (b) - 1; i >= (a); i--)
#define F0Rd(i, a) for (int i = (a) - 1; i >= 0; i--)
#define trav(a, x) for (auto &a : x)
#define sz(x) (int)(x).size()
#define pb push_back
#define f first
#define s second
#define lb lower_bound
#define ub upper_bound
#define all(x) x.begin(), x.end()
#define ins insert

const char nl = '\n';

void solve() {
    int N, M; cin >> N >> M;
    vector<set<int>> graph(N);
    F0R(i, M) {
        int X, Y; cin >> X >> Y;
        X--; Y--;
        graph[X].ins(Y); graph[Y].ins(X);
    }

    bool vis[N]; F0R(i, N) vis[i] = false;
    vpi ans;
    vpi atEntr[N];
    F0R(r, N) {
        if (vis[r]) continue;
        vis[r] = true;
        vi comp;
        int edCount;
        queue<int> q; q.push(r);
        while (!q.empty()) {
            int v = q.front(); q.pop();
            comp.pb(v);
            trav(a, graph[v]) {
                if (vis[a]) continue;
                vis[a] = true;
                q.push(a);
            }
        }
        edCount = 0;
        trav(a, comp) edCount += sz(graph[a]);
        edCount /= 2;
        vpi leafEds;
        trav(a, comp) {
            if (sz(graph[a]) == 1) {
                leafEds.pb({a, *graph[a].begin()});
                q.push(a);
            }
        }
        if (edCount == sz(comp) - 1) {
            trav(a, leafEds) ans.pb(a);
            continue;
        }
        while (!q.empty()) {
            int v = q.front(); q.pop();
            trav(a, graph[v]) {
                graph[a].erase(v);
                atEntr[a].pb({a, v});
                if (sz(graph[a]) == 1) {
                    q.push(a);
                }
            }
        }
        trav(a, comp) {
            if (sz(graph[a]) >= 2) {
                trav(b, atEntr[a]) {
                    ans.pb(b);
                }
            }
        }
    }
    sort(all(ans));
    ans.resize(unique(all(ans)) - ans.begin());
    cout << sz(ans) << nl;
    trav(a, ans) {
        cout << a.f+1 << " " << a.s+1 << nl;
    }
}

int main() {
	ios_base::sync_with_stdio(0); cin.tie(0);
	solve();
	return 0;
}