#include <bits/stdc++.h>
using namespace std;
vector <pair <pair <int, int>, int> > el;
vector <pair <int, int> > newel;
int memo[5000];
int main(){
    int sz;
    int iq;
    int cont = 0;
    while(cin >> sz >> iq){
    	el.push_back(make_pair(make_pair(sz,iq),cont));
    	cont++;
    }
    sort(el.begin(), el.end());
    int aux = el[0].first.second;
    int auxp = el[0].second;
    for(int i=1; i<el.size(); i++){
    	if(el[i].first.first == el[i-1].first.first){
    		if(el[i].first.second > aux){
    			aux = el[i].first.second;
    			auxp = el[i].second;
    		}
    	}
    	else{
    		newel.push_back(make_pair(aux, auxp));
    		aux = el[i].first.second;
    		auxp = el[i].second;
    	}
    }
    for(int i=0; i<newel.size(); i++){
    	cout << newel[i].first << " " << newel[i].second << endl;
    }
    //vector < vector <int> > ans(newel.size());
    //ans[0].push_back(newel[0].second);
    /*for(int i=1; i<newel.size(); i++){
    	for(int j=0; j<i; j++){
    		if((newel[i].first < newel[j].first) && (ans[i].size() < ans[j].size()+1)) ans[i] = ans[j];
    	}
    	ans[i].push_back(newel[i].second);
    }*/
    /*int maxi = ans[0].size();
    int auxp2 = 0;
    for(int i=0; i<ans.size(); i++){
    	if(maxi < ans[i].size()){
    		maxi = ans[i].size();
    		auxp2 = i;
    	}
    	cout << ans[i].size() << endl;
    }*/
    //cout << maxi << '\n';
    /*for(int i=0; i<ans[auxp2].size(); i++){
    	cout << ans[auxp2][i] << '\n';
    }*/
    return 0;
}
 

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1 1
1 2
1 9998
1 9999
1 10000
2 1
2 2
2 9998
2 9999
2 10000
9998 1
9998 2
9998 9998
9998 9999
9998 10000
9999 1
9999 2
9999 9998
9999 9999
9999 10000
10000 1
10000 2
10000 9998
10000 9999
10000 10000
1 1
2 1
9998 1
9999 1
10000 1
1 2
2 2
9998 2
9999 2
10000 2
1 9998
2 9998
9998 9998
9999 9998
10000 9998
1 9999
2 9999
9998 9999
9999 9999
10000 9999
1 10000
2 10000
9998 10000
9999 10000
10000 10000