#include <bits/stdc++.h>
using namespace std;
#define int long long
#define rep(i,n) for(int (i)=0;(i)<(n);(i)++)
#define rrep(i,n) for(int (i)=((n)-1);(i)>=0;(i)--)
#define itn int
#define all(x) (x).begin(),(x).end()
#define F first
#define S second
using P = pair <int,int>;
using WeightedGraph = vector<vector <P>>; //to cost
using UnWeightedGraph = vector<vector<int>>;
const long long INF = 1LL << 60;
const int MOD = 1000000007;
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
#define DUMPOUT cerr
#define repi(itr, ds) for (auto itr = ds.begin(); itr != ds.end(); itr++)
template <typename T, typename U>
istream &operator>>(istream &is, pair<T,U> &p_var) {
    is >> p_var.first >> p_var.second;
    return is;
}
template <typename T>
istream &operator>>(istream &is, vector<T> &vec) {
    for (T &x : vec) is >> x;
    return is;
}
template <typename T>
istream &operator>>(istream &is, vector<vector<T>> &df) {
    for(int i=0;i<df.size();i++)for(int j=0;j<df[i].size();j++)
    is >> df[i][j];
    return is;
}
template <typename T, typename U>
ostream &operator<<(ostream &os, pair<T, U> &pair_var) {
    //DUMPOUT<<'{';
    os << pair_var.first;
    //DUMPOUT<<',';
    os << " "<< pair_var.second;
    //DUMPOUT<<'}';
    return os;
}
template <typename T>
ostream &operator<<(ostream &os, vector<T> &vec) {
    DUMPOUT<<'[';
    for (int i = 0; i < vec.size(); i++) 
    os << vec[i] << (i + 1 == vec.size() ? "" : " ");
    DUMPOUT<<']';
    return os;
}
template <typename T>
ostream &operator<<(ostream &os, vector<vector<T>> &df) {
  for (auto& vec : df) os<<vec;
  return os;
}
template <typename T, typename U>
ostream &operator<<(ostream &os, map<T, U> &map_var) {
    DUMPOUT << "{";
    repi(itr, map_var) {
        os << *itr;
        itr++;
        if (itr != map_var.end()) DUMPOUT << ", ";
        itr--;
    }
    DUMPOUT << "}";
    return os;
}
template <typename T>
ostream &operator<<(ostream &os, set<T> &set_var) {
    DUMPOUT << "{";
    repi(itr, set_var) {
        os << *itr;
        itr++;
        if (itr != set_var.end()) DUMPOUT << ", ";
        itr--;
    }
    DUMPOUT << "}";
    return os;
}
void print() {cout << endl;}
template <class Head, class... Tail>
void print(Head&& head, Tail&&... tail) {
  cout << head;
  if (sizeof...(tail) != 0) cout << " ";
  print(forward<Tail>(tail)...);
}
void dump_func() {DUMPOUT << '#'<<endl;}
template <typename Head, typename... Tail>
void dump_func(Head &&head, Tail &&... tail) {
    DUMPOUT << head;
    if (sizeof...(Tail) > 0) DUMPOUT << ", ";
    dump_func(std::move(tail)...);
}
#ifdef DEBUG_
#define DEB
#define dump(...)                                                              \
    DUMPOUT << "  " << string(#__VA_ARGS__) << ": "                            \
            << "[" << to_string(__LINE__) << ":" << __FUNCTION__ << "]"        \
            << endl                                                            \
            << "    ",                                                         \
        dump_func(__VA_ARGS__)
#else
#define DEB if (false)
#define dump(...)
#endif
template <typename G>
struct Lowlink {
    const G &g;
    vector <int> used, ord, low;
    vector <int> articulation;
    vector <pair<int,int>> bridge;

    Lowlink(const G &g) : g(g){
        used.assign(g.size(), 0);
        ord.assign(g.size(), 0);
        low.assign(g.size(), 0);
        int k = 0;
        for(int i = 0; i < g.size(); i++) {
            if(!used[i]) k = dfs(i, k, -1);
        }
    }

    int dfs(int now, int k, int par){
        used[now] = true, low[now] = ord[now] = k++; 
        bool is_articulation = false;
        int cnt = 0;
        for(auto &to : g[now]){
            if(!used[to]){
                ++cnt;
                k = (dfs(to, k, now));
                low[now] = min(low[now], low[to]);
                is_articulation |= ~par && low[to] >= ord[now];
                if(ord[now]<low[to]) bridge.emplace_back(minmax(now, (int)to));
            }else if(to != par){
                low[now] = min(low[now], ord[to]);
            }
        }
        is_articulation |= par == -1 && cnt > 1;
        if(is_articulation) articulation.push_back(now);
        return k;
    }
};
signed main(void) { cin.tie(0); ios::sync_with_stdio(false);
    int v,e; cin>>v>>e;
    vector <vector<int>> g(v,vector <int>());
    rep(i,e){
        int a,b; cin>>a>>b;
        g[a].push_back(b);
        g[b].push_back(a);
    }
    struct Lowlink <UnWeightedGraph> ll(g);
    auto ans = ll.bridge;
    sort(ans.begin(),ans.end());
    rep(i, ans.size()) print(ans[i]);
    
}



Measured memory_bytes: 5380