#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
//#include "light.h"
#define int long long
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<pii> vii;
typedef vector<bool> vb;
typedef long long ll;
typedef pair<ll,ll> pll;
typedef vector<pll> vll;
typedef tree<pii,null_type,less<pii>,rb_tree_tag,
tree_order_statistics_node_update> oset;
#define fi first
#define se second
#define pb push_back
#define pf push_front
#define mid (l+r)/2
#define all(x) x.begin(),x.end()
#define FOR(i,a) for(int i=0;i<(a);i++)
#define FORE(i,a,b) for(int i=(a);i<(b);i++)
#define cont(x) for(auto el:x) cout<<el<<' ';cout<<endl;
#define contp(x) for(auto el:x) cout<<el.fi<<'-'<<el.se<<' ';cout<<endl;
#define sp <<" "<<
#define DEBUG(x) cout<<(#x) sp x<<endl
#define carp(a,b) (((a%MOD)*(b%MOD))%MOD)
#define topla(a,b) (((a%MOD)+(b%MOD))%MOD)
const ll INF=1e18;
const int MAXN=1e5+5;
const int MOD=1e9+7;
int n,s,t;
int ans;
vii a;
set<int> tut[MAXN];
int bir[MAXN],iki[MAXN];
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin>>n>>s>>t;
a.resize(n);
FOR(i,n){
cin>>a[i].fi>>a[i].se;
if(a[i].fi>a[i].se) swap(a[i].fi,a[i].se);
tut[a[i].fi].insert(i);
tut[a[i].se].insert(i);
}
vb used(n,false);
FOR(j,n){
if(used[j]) continue;
queue<int> q;
q.push(j);
while(!q.empty()){
auto i=q.front();
q.pop();
if(used[i]) continue;
used[i]=true;
tut[a[i].fi].erase(i);
tut[a[i].se].erase(i);
if(bir[a[i].fi]>iki[a[i].fi] or iki[a[i].se]>bir[a[i].se]){
swap(a[i].fi,a[i].se);
}
bir[a[i].fi]++;
iki[a[i].se]++;
if(bir[a[i].fi]!=iki[a[i].fi]){
for(auto el:tut[a[i].fi]){
q.push(el);
}
}
if(bir[a[i].se]!=iki[a[i].se]){
for(auto el:tut[a[i].se]){
q.push(el);
}
}
}
}
for(auto el:a) cout<<el.fi sp el.se<<endl;
}
