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 <iostream>
#include <algorithm>
#define ll long long
using namespace std;

int main(){

  int n, idx = 0;
  ll a[100010] = {};
  ll x[2] = {};
  cin >> n;
  for(int j = 0; j < n; j++) cin >> a[j];
  sort(a, a+n, greater<ll>());
  for(int i = 0; i < n-1; i++){
    if(a[i] == a[i+1]){
      x[idx++] = a[i];
      i++;
    }
  }
  cout << x[0] * x[1] << endl;
  return 0;
}
