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;
inline void read(int &x) {
  short negative = 1;
  x = 0;
  char c = getchar();
  while (c < '0' || c > '9') {
    if (c == '-') negative = -1;
    c = getchar();
  }
  while (c >= '0' && c <= '9')
    x = (x << 3) + (x << 1) + (c ^ 48), c = getchar();
  x *= negative;
}
long long quickpower(long long n, long long k) {
  long long ans = 1;
  while (k) {
    if (k % 2) {
      ans *= n;
      ans %= 1000000007;
    }
    n *= n;
    n %= 1000000007;
    k /= 2;
  }
  return ans;
}
string int_to_string(int n) {
  string s = "";
  while (n) {
    int now = n % 10;
    s += now + '0';
    n /= 10;
  }
  reverse(s.begin(), s.end());
  return s;
}
int string_to_int(string s) {
  int n = 0;
  for (int i = 0, _n = s.size(); i < s.size(); i++) {
    n *= 10;
    n += s[i] - '0';
  }
  return n;
}
bool cmp(string s, string k) {
  if (s.size() == k.size()) return s < k;
  string s1 = s + k, s2 = k + s;
  if (s1 < s2) return 1;
  return 0;
}
int n;
string a[50100];
int main() {
  ios::sync_with_stdio(0);
  cin >> n;
  for (int i = 0, _n = n; i < n; i++) cin >> a[i];
  sort(a, a + n, cmp);
  for (int i = 0, _n = n; i < n; i++) cout << a[i];
  cout << endl;
  return 0;
}