#include <iostream>
#include <ctime>
#include <vector>
#include <algorithm>
#include <cmath>
#include <set>
#include <unordered_set>
#include <map>
#include <string>
#include <queue>
#include <cstdlib>
#include <cstdio>

using namespace std;

#define endl '\n'
#define pb push_back
#define ff first
#define ss second
#define pf push_front
#define INF 1000000009
#define go_fast ios_base::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);
#define ll long long


int main() {
    int N;
    cin >> N;
    set <string> a;
    string peep;
    vector <string> b;
    for (int i = 0; i < N; ++i) {
        cin >> peep;
        a.insert(peep);
        b.push_back(peep);
    }
    set <string> solve;
    sort(b.begin(), b.end());
    for (int i = 0; i < N; ++i) {
        for (int g = 0; g < N; ++g) {
            if (a.find(b[i] + b[g]) != a.end()) solve.insert(b[i] + b[g]);
        }
    }
    for (auto f : solve) cout << f << endl;
    return 0;

}