//雪花飄飄北風嘯嘯
//天地一片蒼茫
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/rope>
using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;
#define ll long long
#define ii pair<ll,ll>
#define iii pair<ii,ll>
#define fi first
#define se second
#define endl '\n'
#define debug(x) cout << #x << " is " << x << endl;
#define rep(x,start,end) for(auto x=(start)-((start)>(end));x!=(end)-((start)>(end));((start)<(end)?x++:x--))
#define all(x) (x).begin(),(x).end()
#define sz(x) (int)(x).size()
ll MAX(ll a){return a;}
ll MIN(ll a){return a;}
template<typename... Args>
ll MAX(ll a,Args... args){return max(a,MAX(args...));}
template<typename... Args>
ll MIN(ll a,Args... args){return min(a,MIN(args...));}
#define indexed_set tree<ll,null_type,less<ll>,rb_tree_tag,tree_order_statistics_node_update>
mt19937 rng(chrono::system_clock::now().time_since_epoch().count());
struct ufds{
int p[100005];
int r[100005];
ufds(){
for (int x=0;x<100005;x++){
p[x]=x;
r[x]=0;
}
}
int parent(int i){return (p[i]==i)?i:p[i]=parent(p[i]);}
void unions(int i,int j){
i=parent(i),j=parent(j);
if (i==j) return;
if (r[i]<r[j]){
p[i]=j;
}
else{
p[j]=i;
if (r[i]==r[j]) r[i]++;
}
}
}dsu=ufds();
struct node{
int s,e,m;
bool val=false;
node *l,*r;
node (int _s,int _e){
s=_s,e=_e,m=s+e>>1;
if (s!=e){
l=new node(s,m);
r=new node(m+1,e);
}
}
void update(int i,int j){
if (s==i && e==j) val=true;
else if (j<=m) l->update(i,j);
else if (m<i) r->update(i,j);
else l->update(i,m),r->update(m+1,j);
}
bool query(int i){
if (val) return true;
else if (s==e) return false;
else if (i<=m && l->query(i)) return true;
else if (m<i && r->query(i)) return true;
else return false;
}
} *root=new node(0,100005);
int n,m;
vector<int> al[100005];
int in[100005]; //preorder
int st[100005]; //subtree size
int parent[100005]; //first parent
int hparent[100005]; //parent on heavy path
int depth[100005];
void dfs_st(int i,int p){
parent[i]=p;
st[i]=1;
if (al[i][0]==p && al[i].size()>1) swap(al[i][0],al[i][1]);
for (auto &it:al[i]){ ///& is important here
if (it==p) continue;
depth[it]=depth[i]+1;
dfs_st(it,i);
st[i]+=st[it];
if (st[it]>st[al[i][0]]){
swap(it,al[i][0]);
//we ensure heavy child is al[i][0]
}
}
}
int dfs_time=0;
void dfs_hld(int i,int p){
in[i]=++dfs_time;
for (auto it:al[i]){
if (it==p) continue;
hparent[it]=(it==al[i][0])?hparent[i]:it;
dfs_hld(it,i);
}
}
void hld_query(int i,int j){
while (hparent[i]!=hparent[j]){
if (depth[hparent[i]]<depth[hparent[j]]) swap(i,j);
//cerr<<"debug: "<<in[hparent[i]]<<" "<<in[i]<<endl;
root->update(in[hparent[i]],in[i]);
i=parent[hparent[i]];
}
if (in[i]>in[j]) swap(i,j);
//cerr<<"debug: "<<in[i]+1<<" "<<in[j]<<endl;
if (in[i]!=in[j]) root->update(in[i]+1,in[j]);
}
vector<int> span;
int main(){
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin>>n>>m;
int a,b;
rep(x,0,m){
cin>>a>>b;
if (dsu.parent(a)!=dsu.parent(b)){
al[a].push_back(b);
al[b].push_back(a);
dsu.unions(a,b);
span.push_back(x);
}
}
rep(x,1,n+1) if (!depth[x]){
depth[x]=1;
parent[x]=0;
hparent[x]=1;
if (!al[x].empty()){
dfs_st(x,-1);
dfs_hld(x,-1);
}
}
//rep(x,1,n+1) cout<<x<<" "<<in[x]<<endl;
cin.seekg(0, ios::beg);
int idx=0;
cin>>n>>m;
rep(x,0,m){
cin>>a>>b;
if (idx!=sz(span) && span[idx]==x){
idx++;
continue;
}
else{
hld_query(a,b);
}
}
rep(x,1,n+1) if (depth[x]!=1){
if (!root->query(in[x])) cout<<x<<" "<<parent[x]<<endl;
}
}
