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>
using namespace std;

int main(){
  int n, a[100000], cnt;
  long long ans[2] = {};
  
  cin >> n;
  for(int i = 0;i < n;i++) cin >> a[i];
  
  sort(a, a + n);
  
  cnt = 0;
  for(int i = n - 1;i > 0;i--){
    if(a[i] == a[i - 1]){
      ans[cnt++] = a[i];
      i--;
    }
    if(cnt == 2) break;
  }
  
  cout << ans[0] * ans[1] << endl;
  
  return 0;
}