C

#include <iostream>
#include <iomanip>
#include <string>
#include <sstream>
#include <algorithm>
#include <vector>
#include <stdlib.h>
#include <stdio.h>
#include <fstream>
#include <stack>
#include <map>
#include <cstring>
#include <cmath>
#include <set>
#include <iterator>
#include <cmath>

using namespace std;

istream & operator >> (istream & in, vector<int> & v)
{
    string str;
    getline(in,str);
    stringstream stream(str);
    int tmp;
    while(stream >> tmp)
        v.push_back(tmp);
    return in;
}


int main()
{
    map<string, string> d;
    int N;
    string a, b;
    cin >> N;
    for(auto i = 0; i < N; ++i)
    {
        cin >> a >> b;
        d[a] = b;
        d[b] = a;
    }
    cin >> a;
    cout << d[a];
    return 0;
}