#include <cstdio>
#include <iostream>
#include <string>
#include <sstream>
#include <stack>
#include <algorithm>
#include <cmath>
#include <queue>
#include <map>
#include <set>
#include <cstdlib>
#include <bitset>
#include <tuple>
#include <assert.h>
#include <deque>
#include <bitset>
#include <iomanip>
#include <limits>
#include <chrono>
#include <random>
#include <array>
#include <unordered_map>
#include <functional>
#include <complex>
#include <numeric>
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
//constexpr long long MAX = 5100000;
constexpr long long INF = 1LL << 60;
constexpr int inf = 1000000007;
constexpr long long mod = 1000000007LL;
//constexpr long long mod = 998244353LL;
const long double PI = acos((long double)(-1));

using namespace std;
typedef unsigned long long ull;
typedef long long ll;
typedef long double ld;


int main()
{
    
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    

    int n; cin >> n;
    char uni = '{';
    vector<string> vs(n); for (int i = 0; i < n; i++) cin >> vs[i], vs[i] += '{';
    vector<priority_queue<string, vector<string>, greater<>>> vpq(26);
    int kkt = 0;
    for (int i = 0; i < n; i++) {
        kkt += vs[i].size() - 1;
        vpq[vs[i][0] - 'a'].emplace(vs[i].substr(1, (int)vs[i].size() - 1));
    }
    string res;
    while (kkt--) {
        for (int i = 0; i < 26; i++) {
            if (!vpq[i].empty()) {
                string s = vpq[i].top();
                vpq[i].pop();
                res += (char)('a' + i);
                if (s[0] == uni) break;
                vpq[s[0] - 'a'].emplace(s.substr(1, (int)s.size() - 1));
               
                break;
            }
        }
    }
    cout << res << endl;
    return 0;
}