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> a(100100);
  long s[3] = {0};
  for(int i = 0;i < n;i++){
    cin >> a.at(i);
  }
  sort(a.begin(),a.end());
  reverse(a.begin(),a.end());
  
  int i = 0,j = 0;
  while(j <= 2){
    if(a.at(i) == a.at(i+1)){
      s[j] = a[i];
      j++;
      i++;
    }
    i++;
    if(i == n){
      break;
    }
  }
  cout << s[0]*s[1] << endl;
}