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>
using namespace std;

int main() {
int n,a[100000],b=0;
long long x=0,y=0;
cin>>n;
for(int i=0;i<n;i++){
    cin>>a[i];
}
sort(a,a+n,greater<int>());
for(int i=0;i<n;i++){
    if(a[i]==b){
        if(x==0){
            x=b;
            b=0;
        }else{
            y=b;
            i=n;
        }
    }else{
        b=a[i];
    }
}
cout<<x*y<<endl;
	return 0;
}