#include <bits/stdc++.h>
#pragma GCC optimize ("O3")

using namespace std;
using ll = long long;

const int MAXN = 3e5 + 1488;

vector<int> gr[MAXN];
vector<int> t;
vector<bool> used(MAXN);
vector<int> tin(MAXN);
vector<int> fup(MAXN);

int timer = 0;

void DFS(int v, int p = -1) {
    cout << "enter v " << v << endl;
    used[v] = true;
    fup[v] = tin[v] = timer++;
    for (int i = 0; i < gr[v].size(); ++i) {
        int to = gr[v][i];
        if (to == p) {
            continue;
        } else if (used[to]) {
            cout << "used to " << to << endl;
            cout << fup[v] << " " << tin[to] << "\n\n";
            fup[v] = min(fup[v], tin[to]);
        } else {
            DFS(to, v);
            cout << "v = " << v << endl;
            cout << fup[v] << " " << fup[to] << "\n\n";
            fup[v] = min(fup[v], fup[to]);
            if (fup[to] > tin[v]) {
                cout << v << " " << to << endl;
            }
        }
    }
}

int main() {
    freopen("a.in", "r", stdin), freopen("a.out", "w", stdout);
    ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
    int n, m;
    cin >> n >> m;
    for (int i = 0; i < m; ++i) {
        int a, b;
        cin >> a >> b;
        gr[a].push_back(b);
        gr[b].push_back(a);
    }
    DFS(1);
    cout << endl;
    // for (int i = 1; i <= n; ++i) {
    //     cout << "i = " << i << "   " << tin[i] << " " << fup[i] << endl;
    // }
    return 0;
}