#include <bits/stdc++.h>
typedef long long ll;
using namespace std;
 
int main() 
{
	ll n, t;
	cin>>t;
	while(t--)
	{
		cin>>n;
		unordered_map<string, ll>u_map;
		// unordered_map<string, string>u_map2;
		vector<pair<string, string> > V;
 
		string s1, s2;
 
		while(n--)
		{
			cin>>s1;
			u_map[s1]++;
			cin>>s2;
			// u_map2[s2] = s1+" "+s2;
			V.push_back({s1, s2});
		}
 
		for( auto u:V)
		{
			if(u_map[u.first]>1)
			{
				cout<<u.first<<" "<<u.second<<endl;
			}
 
			else
			{
				cout<<u.first<<endl;
			}
		}
 
	}
 
	return 0;
}

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hasan jaddouh
farhod khakimiyon
kerim kochekov
hasan khateeb