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;
using ll = long long int;

int main(void){
  int n; cin >> n;
  vector<int> a(n);
  ll ver = 0, hol = 0;
  
  for(int i = 0;i < n;i++) cin >> a[i];
  
  sort(a.begin(), a.end(), greater<int>());
  
  for(int i = 0;i < n-1;i++){
    if(a[i] == a[i+1]){
      if(ver == 0) ver = a[i];
      else if(hol == 0) hol = a[i];
      i++;
    }
  }
  
  cout << ver * hol << endl;
}