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 outFloat {
  int precision;
  long double value;
  outFloat(long double v, int p) : precision(p), value(v) {}
};
const int inf = 123456789;
const long long llInf = 123456789012345678;
const long double pi = 3.14159265358979323846;
const int maxN = 2000000;
int init() {
  ios_base::sync_with_stdio(0);
  srand(time(NULL));
  return 0;
}
int initializer = init();
template <typename T1, typename T2>
istream &operator>>(istream &is, pair<T1, T2> &p) {
  is >> p.first >> p.second;
  return is;
}
template <typename T>
istream &operator>>(istream &is, vector<T> &p) {
  for (int i = 0; i < p.size(); i++) is >> p[i];
  return is;
}
class inputer {
 private:
  istream *istr;

 public:
  inputer(istream &is) : istr(&is) {}
  template <typename T>
  void get(T &n) {
    (*istr) >> n;
  }
  template <typename T, typename... Args>
  void get(T &n, Args &...args) {
    get(n);
    get(args...);
  }
  template <typename... Args>
  void getLn(Args &...args) {
    get(args...);
    getLn();
  }
  template <typename T>
  operator T() {
    T n;
    get(n);
    return n;
  }
  void getLn() {
    string s;
    getline(cin, s);
  }
  template <typename T>
  void getv(vector<T> &v, int size) {
    v.resize(size);
    (*istr) >> v;
  }
};
string delim = " ";
template <typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p) {
  os << p.first << delim << p.second;
  return os;
}
template <typename T>
ostream &operator<<(ostream &os, const vector<T> &p) {
  for (int i = 0; i < p.size(); i++) {
    if (i != 0) os << delim;
    os << p[i];
  }
  return os;
}
ostream &operator<<(ostream &os, const outFloat &of) {
  os << setprecision(of.precision) << of.value;
  return os;
}
class outputer {
 private:
  ostream *ostr;

 public:
  outputer(ostream &os) : ostr(&os) {}
  template <typename T>
  void put(const T &n) {
    (*ostr) << n;
  }
  template <typename T, typename... Args>
  void put(const T &n, const Args &...args) {
    put(n);
    put(args...);
  }
  template <typename... Args>
  void putLn(const Args &...args) {
    put(args...);
    putLn();
  }
  template <typename T>
  outputer &operator=(const T &n) {
    put(n);
    return *this;
  }
  void putLn() { (*ostr) << "\n"; }
  template <typename T>
  void putv(vector<T> v, int size, string delim) {
    for (int i = 0; i < size; i++) {
      if (i != 0) (*ostr) << delim;
      (*ostr) << v[i];
    }
  }
};
inputer in(cin);
outputer out(cout);
char getChar() {
  char c = 0;
  while (c <= ' ') cin >> c;
  return c;
}
bool willItBeAC() {
  return true;
  ;
}
int getMyRating() { return 2121; }
bool prime(long long n) {
  for (long long i = 2; i * i <= n; i++)
    if (n % i == 0) return false;
  return true;
}
vector<long long> divs(long long n) {
  vector<long long> v;
  long long i = 2;
  while (i * i <= n)
    if (n % i == 0) {
      n /= i;
      v.push_back(i);
    } else
      i++;
  v.push_back(n);
  return v;
}
long long gcd(long long a, long long b) { return b ? gcd(b, a % b) : a; }
long long extGcd(long long a, long long b, long long &x, long long &y) {
  if (a == 0) {
    x = 0;
    y = 1;
    return b;
  }
  long long x1, y1, d = extGcd(b % a, a, x1, y1);
  x = y1 - (b / a) * x1;
  y = x1;
  return d;
}
template <typename T>
class fenwick {
 private:
  vector<T> t;
  int n;

 public:
  fenwick(int nn) { init(nn); }
  void init(int nn) {
    n = nn;
    t.assign(n, 0);
  }
  T sum(int r) {
    T result = 0;
    for (; r >= 0; r = (r & (r + 1)) - 1) result += t[r];
    return result;
  }
  void inc(int i, T delta) {
    for (; i < n; i = (i | (i + 1))) t[i] += delta;
  }
  T sum(int l, int r) { return sum(r) - sum(l - 1); }
  T get(int i) { return sum(i, i); }
  void put(int i, T v) { inc(i, v - sum(i, i)); }
  int size() { return n; }
};
bool cmp(const string &a, const string &b) { return a + b < b + a; }
int main() {
  int n = in;
  vector<string> v;
  in.getv(v, n);
  sort(v.begin(), v.end(), cmp);
  for (int i = 0; i < n; i++) out = v[i];
  return 0;
}