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,acnt=0,bcnt=0;
 cin >> n;
  vector<long long> a(n);
  for(int i=0;i<n;i++){
    cin >> a[i];
  }
  long long b=0,c=0;

  sort(a.begin(),a.end(),greater<long long>());
    for(int i=0;i<n;i++){
      if(a[i]==a[i+1]){
        if(b==0)b=a[i];
        else if(c==0)c=a[i];
        i++;
      }
    }
    cout <<  (long long)b*c << endl;
  }
