Problem: You're given a list of n strings a1, a2, ..., an. You'd like to concatenate them together in some order such that the resulting string would be lexicographically smallest.

Given the list of strings, output the lexicographically smallest concatenation.

Input

The first line contains integer n — the number of strings (1 ≤ n ≤ 5·104).

Each of the next n lines contains one string ai (1 ≤ |ai| ≤ 50) consisting of only lowercase English letters. The sum of string lengths will not exceed 5·104.

Output

Print the only string a — the lexicographically smallest string concatenation.

Examples

Input

4
abba
abacaba
bcd
er


Output

abacabaabbabcder


Input

5
x
xx
xxa
xxaa
xxaaa


Output

xxaaaxxaaxxaxxx


Input

3
c
cb
cba


Output

cbacbc

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
bool less_vectors(const vector<long long>& a, const vector<long long>& b) {
  return a.size() < b.size();
}
struct Comparator {
  bool operator()(const std::pair<long long, long long>& lhs,
                  const std::pair<long long, long long>& rhs) const {
    if (lhs.first != rhs.first)
      return lhs.first < rhs.first;
    else
      return lhs.second < rhs.second;
  }
};
long long fastexpo(long long a, long long b) {
  long long res = 1;
  while (b > 0) {
    if (b % 2 == 1) res = ((res) % 1000000009 * (a) % 1000000009) % 1000000009;
    a = ((a) % 1000000009 * (a) % 1000000009) % 1000000009;
    b /= 2;
  }
  return res;
}
long long fastexpom(long long a, long long b, long long m) {
  long long res = 1;
  while (b > 0) {
    if (b % 2 == 1) res = (((res) % m) * ((a) % m)) % m;
    a = (((a) % m) * ((a) % m)) % m;
    b /= 2;
  }
  return res;
}
long long modinv(long long a, long long m = 1000000009) {
  return fastexpom(a, m - 2, m);
}
bool comp(string s1, string s2) { return s1 + s2 < s2 + s1; }
int32_t main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  long long n;
  cin >> n;
  vector<string> v(n);
  for (long long i = 0; i < n; i++) cin >> v[i];
  sort(v.begin(), v.end(), comp);
  for (long long i = 0; i < n; i++) cout << v[i];
  return 0;
}