#include <bits/stdc++.h>

using namespace std;
string S[100];

bool check(const string &a, const string &b) {
  const string ab = a + b, ba = b + a;
  if (stoi(ab) < stoi(ba))
    return false;
  return true;
}

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  freopen("B4.INP", "r", stdin);

  int n;
  cin >> n;
  for (int i = 0; i < n; i++) {
    string a;
    cin >> a;
    S[i] = a;
  }

  sort(S, S + n, check);
  for (int i = 0; i < n; i++) {
    cout << S[i];
  }
  cout << '\n';
}