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<long long>A(N); for(int i=0;i<N;i++) cin>>A.at(i);
  
  sort(A.begin(),A.end());
  
  vector<long long>side(N);
  int j=0;
  
  for(int i=0;i<N-1;i++){
    if(A.at(i)==A.at(i+1)){
      side.at(j)=A.at(i);
      j++;
      i++;
    }
  }
  
  sort(side.begin(),side.end());
  reverse(side.begin(),side.end());
  
  cout<<side.at(0)*side.at(1);
}