#include <bits/stdc++.h>
#define F first
#define S second
#define mp make_pair
#define pb push_back
#define sz(x) (int)x.size()
using namespace std;
typedef long long ll;
typedef long double ld;
const int N = (int)2e5 + 123;
const int mod = (int)1e9 + 7;
const ll inf = 1e18 + 9;
inline void boost () {
ios_base::sync_with_stdio (0);
cin.tie (0), cout.tie (0);
}
int n, m;
vector < vector < int > > g;
vector < bool > used;
vector < int > tin, fup;
int timer;
map < pair < int , int >, int > cnt;
vector < pair < int, int > > ans;
void dfs (int v, int pr = 0) {
used[v] = 1;
tin[v] = fup[v] = ++ timer;
for (auto to : g[v]) {
if (to == pr) continue;
if (used[to]) {
fup[v] = min (fup[v], tin[to]);
} else {
dfs (to, v);
fup[v] = min (fup[v], fup[to]);
if (fup[to] > tin[v] && cnt[mp (v, to)] <= 1) {
ans.pb (mp (v, to));
}
}
}
}
int main () {
boost ();
cin >> n >> m;
int u, v;
g.resize (n + 1);
used.resize (n + 1);
tin.resize (n + 1);
fup.resize (n + 1);
for (int i = 1;i <= m;i ++) {
cin >> u >> v;
g[u].pb (v);
g[v].pb (u);
cnt[mp (u, v)] ++;
cnt[mp (v, u)] ++;
}
for (int i = 1;i <= n;i ++) {
if (!used[i]) dfs (i);
}
for (auto it : ans) cout << it.F << ' ' << it.S << endl;
return 0;
}
