1389

#include <iostream>
#include <vector>
#include <algorithm>
#include <unordered_map>
using namespace std;

long long int n, m, h = 2433137;

vector <vector <int>> g;
vector <int> f;
unordered_map <long long int, pair<int, int>> d;

pair <int, bool> rek( int u,  int v) {
    if (g[u].size() > 1 || u == 1) {

        bool trig = false;
        int res = 0;

        for (auto i : g[u]) {
            if (i != v) {

                pair < int, bool> t = rek(i, u);

                f[i] = 1;
                res += t.first;

                if (!t.second) {
                    if (!trig) {
                        trig = true;
                        res++;
                        f[i] = 2;
                    }
                }
            }
        }

        return { res , trig };
    }
    else {
        return {0, false};
    }
}

void rekk(int u, int v) {
    if (g[u].size() > 1 || u == 1) {

        bool trig = true;

        for (auto i : g[u]) {
            if (i != v) {

                rekk(i, u);

                if (f[i] == 2) {
                    cout << d[u * h + i].first << " " << d[u * h + i].second << "\n";
                }
            }
        }

    }
}

int main()
{
    iostream::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);

    cin >> n >> m;

    g.resize(n + 1, f);
    f.resize(n + 3, 0);

    for (int i = 0; i < m; i++) {
        int a, b;

        cin >> a >> b;

        g[a].push_back(b);
        g[b].push_back(a);

        d[a * h + b] = { a, b };
        d[b * h + a] = { a, b };
    }

    cout << rek(1, 0).first << "\n";
    rekk(1, 0);
}