#include<bits/stdc++.h>
using namespace std;
int main()
{
    vector<pair<int, string> > stu;
    string s;
    int n,t;
    cin>>n;
    for(int i = 0; i <n; ++i){
        cin>>t;
        cin>>s;
        stu.push_back(make_pair(t,s));
    }
    int vis[n];
    memset(vis,0,sizeof(vis));
    for(int i=0; i<n/2; ++i){
        cout<<stu[i].second;
        for(int j = n-1; j>=n/2; j--){
            if(stu[i].first ^ stu[j].first && !vis[j]){
                cout<<" "<<stu[j].second<<endl;
                vis[j] = 1;
                break;
            }
        }
    }
    return 0;

}