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 long int a[5000000],n,b,c[2],d;
int main(){
    cin>>n;
    for(int i=0;i<n;i++){
        cin>>a[i];
    }
    sort(a,a+n);
    reverse(a,a+n);
    while(1){
        if(d==2)break;
        if(a[b]==a[b+1]){c[d]=a[b];d++;b++;}
        b++;
    }
    cout<<c[0]*c[1]<<endl;

}
