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<iostream>
#include <algorithm>
#include <string>
using namespace std;

int main()
{int N;
 cin >> N;
 long long C[N];
 long long h=0;
 long long w=0;
 int count =0;
 for(int i=0; i<N; i++){
   cin >> C[i];}
 sort(C, C+N, greater<int>());
 for(int i=0; i<N-1; ++i){
   if(C[i]==C[i+1]){
     if(h==0){
       h=C[i];
     	++i;
     	}
     else{
       w=C[i];
     	break;}}}
 cout << h*w << endl;
      
}