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;
struct edge {
  long long to, cost;
  edge() {}
  edge(long long a, long long b) { to = a, cost = b; }
};
const long long dx[] = {1, 0, -1, 0}, dy[] = {0, -1, 0, 1};
const long long mod = 1000000007;
struct mint {
  long long x = 0;
  mint(long long y = 0) {
    x = y;
    if (x < 0 || x >= mod) x = (x % mod + mod) % mod;
  }
  mint(const mint& ope) { x = ope.x; }
  mint operator-() { return mint(-x); }
  mint operator+(const mint& ope) { return mint(x) += ope; }
  mint operator-(const mint& ope) { return mint(x) -= ope; }
  mint operator*(const mint& ope) { return mint(x) *= ope; }
  mint operator/(const mint& ope) { return mint(x) /= ope; }
  mint& operator+=(const mint& ope) {
    x += ope.x;
    if (x >= mod) x -= mod;
    return *this;
  }
  mint& operator-=(const mint& ope) {
    x += mod - ope.x;
    if (x >= mod) x -= mod;
    return *this;
  }
  mint& operator*=(const mint& ope) {
    x *= ope.x, x %= mod;
    return *this;
  }
  mint& operator/=(const mint& ope) {
    long long n = mod - 2;
    mint mul = ope;
    while (n) {
      if (n & 1) *this *= mul;
      mul *= mul;
      n >>= 1;
    }
    return *this;
  }
  mint inverse() { return mint(1) / *this; }
  bool operator==(const mint& ope) { return x == ope.x; }
  bool operator!=(const mint& ope) { return x != ope.x; }
  bool operator<(const mint& ope) { return x < ope.x; }
};
mint modpow(mint a, long long n) {
  if (n == 0) return mint(1);
  if (n % 2)
    return a * modpow(a, n - 1);
  else
    return modpow(a * a, n / 2);
}
istream& operator>>(istream& is, mint& ope) {
  long long t;
  is >> t, ope.x = t;
  return is;
}
ostream& operator<<(ostream& os, mint& ope) { return os << ope.x; }
ostream& operator<<(ostream& os, const mint& ope) { return os << ope.x; }
vector<mint> fact, fact_inv;
void make_fact(int n) {
  fact.resize(n + 1), fact_inv.resize(n + 1);
  fact[0] = mint(1);
  for (long long i = (1); (i) <= (n); (i)++) fact[i] = fact[i - 1] * mint(i);
  fact_inv[n] = fact[n].inverse();
  for (long long i = (n - 1); (i) >= (0); (i)--)
    fact_inv[i] = fact_inv[i + 1] * mint(i + 1);
}
mint comb(long long n, long long k) {
  if (n < 0 || k < 0 || n < k) return mint(0);
  return fact[n] * fact_inv[k] * fact_inv[n - k];
}
mint perm(long long n, long long k) { return comb(n, k) * fact[k]; }
vector<int> prime, pvec;
void make_prime(int n) {
  prime.resize(n + 1);
  for (long long i = (2); (i) <= (n); (i)++) {
    if (prime[i]) continue;
    for (int j = i; j <= n; j += i) prime[j] = i;
  }
  for (long long i = (2); (i) <= (n); (i)++)
    if (prime[i] == i) pvec.push_back(i);
}
bool exceed(long long x, long long y, long long m) { return x >= m / y + 1; }
void mark() { cout << "*" << endl; }
void yes() { cout << "YES" << endl; }
void no() { cout << "NO" << endl; }
long long sgn(long long x) {
  if (x > 0) return 1;
  if (x < 0) return -1;
  return 0;
}
long long gcd(long long a, long long b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
long long lcm(long long a, long long b) { return a / gcd(a, b) * b; }
long long digitnum(long long x, long long b = 10) {
  long long ret = 0;
  for (; x; x /= b) ret++;
  return ret;
}
long long digitsum(long long x, long long b = 10) {
  long long ret = 0;
  for (; x; x /= b) ret += x % b;
  return ret;
}
string lltos(long long x) {
  string ret;
  for (; x; x /= 10) ret += x % 10 + '0';
  reverse(ret.begin(), ret.end());
  return ret;
}
long long stoll(string& s) {
  long long ret = 0;
  for (auto c : s) ret *= 10, ret += c - '0';
  return ret;
}
template <typename T>
void uniq(T& vec) {
  sort(vec.begin(), vec.end());
  vec.erase(unique(vec.begin(), vec.end()), vec.end());
}
template <class S, class T>
pair<S, T>& operator+=(pair<S, T>& s, const pair<S, T>& t) {
  s.first += t.first, s.second += t.second;
  return s;
}
template <class S, class T>
pair<S, T>& operator-=(pair<S, T>& s, const pair<S, T>& t) {
  s.first -= t.first, s.second -= t.second;
  return s;
}
template <class S, class T>
pair<S, T> operator+(const pair<S, T>& s, const pair<S, T>& t) {
  return pair<S, T>(s.first + t.first, s.second + t.second);
}
template <class S, class T>
pair<S, T> operator-(const pair<S, T>& s, const pair<S, T>& t) {
  return pair<S, T>(s.first - t.first, s.second - t.second);
}
template <typename T>
ostream& operator<<(ostream& os, vector<T>& vec) {
  for (int i = 0; i < vec.size(); i++)
    os << vec[i] << (i + 1 == vec.size() ? "" : " ");
  return os;
}
template <typename T>
ostream& operator<<(ostream& os, deque<T>& deq) {
  for (int i = 0; i < deq.size(); i++)
    os << deq[i] << (i + 1 == deq.size() ? "" : " ");
  return os;
}
template <typename T, typename U>
ostream& operator<<(ostream& os, pair<T, U>& pair_var) {
  os << "(" << pair_var.first << ", " << pair_var.second << ")";
  return os;
}
template <typename T, typename U>
ostream& operator<<(ostream& os, const pair<T, U>& pair_var) {
  os << "(" << pair_var.first << ", " << pair_var.second << ")";
  return os;
}
template <typename T, typename U>
ostream& operator<<(ostream& os, map<T, U>& map_var) {
  for (typename map<T, U>::iterator itr = map_var.begin(); itr != map_var.end();
       itr++) {
    os << "(" << itr->first << ", " << itr->second << ")";
    itr++;
    if (itr != map_var.end()) os << ",";
    itr--;
  }
  return os;
}
template <typename T>
ostream& operator<<(ostream& os, set<T>& set_var) {
  for (typename set<T>::iterator itr = set_var.begin(); itr != set_var.end();
       itr++) {
    os << *itr;
    ++itr;
    if (itr != set_var.end()) os << " ";
    itr--;
  }
  return os;
}
template <typename T>
ostream& operator<<(ostream& os, multiset<T>& set_var) {
  for (typename multiset<T>::iterator itr = set_var.begin();
       itr != set_var.end(); itr++) {
    os << *itr;
    ++itr;
    if (itr != set_var.end()) os << " ";
    itr--;
  }
  return os;
}
template <typename T>
void outa(T a[], long long s, long long t) {
  for (long long i = s; i <= t; i++) {
    cout << a[i];
    if (i < t) cout << " ";
  }
  cout << endl;
}
void dump_func() { cout << endl; }
template <class Head, class... Tail>
void dump_func(Head&& head, Tail&&... tail) {
  cout << head;
  if (sizeof...(Tail) > 0) cout << " ";
  dump_func(std::move(tail)...);
}
long long n;
string s[50005];
bool comp(string s, string t) { return s + t < t + s; }
int main(void) {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cin >> n;
  for (long long i = (1); (i) <= (n); (i)++) cin >> s[i];
  sort(s + 1, s + n + 1, comp);
  string ans;
  for (long long i = (1); (i) <= (n); (i)++) ans += s[i];
  dump_func(ans);
  return 0;
}