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(){
  long long n,h=0,w=0;
  cin >> n;
  map<long long,int> m;
  for(int i=0;i<n;i++){
    long long a;
    cin >> a;
    m[a]++;
    if(m[a]==2){
      if(a>=h){
        w=h;
        h=a;
      }
      else if(a>w){
        w=a;
      }
      m[a]-=2;
    }
  }
  cout << h*w << endl;
}