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;

long v[1<<20],n,e1=0;

int main(){
    cin>>n;
    for(int i=0;i < n;i++)
    {
        cin>>v[i];v[i]*=-1;
    }

    sort(v,v+n);

    for(int i=0;i < n-1;i++)
    {
        if(v[i]==v[i+1]){
            if(e1){
                cout<<e1*v[i];return 0;
            }else{
                e1=v[i];
                i++;
            }
        }
    }
    cout<<0<<endl;

}