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,s,count;
  s=1;
  count=0;
  cin >> N;
  vector<long long> A(N);
  for(long long i=0;i<N;i++){cin >> A[i];}
  sort(A.begin(), A.end());
  for(long long i=N-1;i>=0;i--){
    if(A[i-1]==A[i]){
      count++; 
      s*=A[i];
      i--;
    }
    if(count==2){
      cout << s << endl;
      return 0;
    }
  }
  cout << 0 << endl;
}