#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<ll, ll> P;
typedef pair<pair<int, int>, int> PP;
const ll INF = 1LL << 60;
const ll MOD = 1000000007;

int GCD(int a, int b) { return b ? GCD(b, a%b) : a; }
//------------------------------------------------------------------------------------------------------------------------------

int main(void) { 
    int N;
    cin >> N;
    set<string> st;
    map<string, bool> cheat;
    for(int i = 0; i < N; i++) {
        string a, b;
        cin >> a >> b;
        cheat[a] = true;
        st.insert(a);
        st.insert(b);
    }
    for (auto itr = st.begin(); itr != st.end(); itr++) {
        if (cheat[*itr]) cout << *itr << endl;
    }
}