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<int> A(N);
  for(int i = 0; i < N; i++){
    cin >> A[i];
  }
  sort(A.begin(), A.end(), greater<int>());
  
  long long s1 = 0, s2 = 0;
  
  for(int i = 0; i < N - 1; i++){
    if(A[i] == A[i+1]) {
      if(s1) {
        s2 = (long long)A[i];
        break;
      }else{
        s1 = (long long)A[i];
      }
      i++;
    }
  }
  
  cout << s1 * s2;
}