#include <iostream>
#include <string>
#include <vector>
using namespace std;
int main(int argc, char* argv[])
{
	int N,i,j;
	cin>>N;
	vector<string> AB;
	vector<int> flag;
	string A,B;
	for (i=0;i<N;i++){
		cin>>A>>B;
		bool bFindA=false;
		bool bFindB=false;
		for (j=0;j<AB.size();j++){
			if (!AB[j].compare(A)){
				flag[j]=1;
				bFindA=true;
			}
			if (!AB[j].compare(B)){
				bFindB=true;
			}
		}
		if (!bFindA){
			AB.push_back(A);
			flag.push_back(1);
		}
		if (!bFindB){				
			AB.push_back(B);
			flag.push_back(0);
		}
	}
	for (i=0;i<AB.size();i++){
		if (flag[i]==0){
			cout<<AB[i]<<endl;
		}
	}
	return 0;
}