#include <bits/stdc++.h>
using namespace std;
int main() {
  const int SIZE = 27;
  const string STR = "abcdefghijklmnopqrstuvwxyz";
  vector<bool> resultMustHave(SIZE, false);
  vector<int> pr(SIZE, -1), next(SIZE, -1);
  int n;
  string s;
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> s;
    for (int j = 0; j < s.size(); j++) {
      int curChar = s[j] - 'a';
      resultMustHave[curChar] = true;
      if (j > 0) {
        int predChar = s[j - 1] - 'a';
        next[predChar] = curChar;
        pr[curChar] = predChar;
      }
    }
  }
  for (int c = 0; c < 26; c++)
    if (resultMustHave[c] && pr[c] == -1)
      for (int j = c; j != -1; j = next[j]) cout << STR[j];
}
