We have N sticks with negligible thickness. The length of the i-th stick is A_i.

Snuke wants to select four different sticks from these sticks and form a rectangle (including a square), using the sticks as its sides. Find the maximum possible area of the rectangle.

Constraints

* 4 \leq N \leq 10^5
* 1 \leq A_i \leq 10^9
* A_i is an integer.

Input

Input is given from Standard Input in the following format:


N
A_1 A_2 ... A_N


Output

Print the maximum possible area of the rectangle. If no rectangle can be formed, print 0.

Examples

Input

6
3 1 2 4 2 1


Output

2


Input

4
1 2 3 4


Output

0


Input

10
3 3 3 3 4 4 4 5 5 5


Output

20
#include <bits/stdc++.h>
using namespace std;

int main() {
  int n;
  cin >> n;
  vector<long long int> A(n);
  map<long long int, int> count;
  vector<long long int> side(0);
  for(int i=0;i<n;i++) {
    cin >> A[i];
    count[A[i]]++;
    if(count[A[i]] % 2 == 0) side.push_back(A[i]);
  }

  sort(side.rbegin(), side.rend());

  if(side.size() < 2) cout << 0 << endl;
  else cout << side[0] * side[1] << endl;
}