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<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;
long long int a[100000+10];
int main()
{
    int n,c=0;
    long long int i,s=1,b[6];
    cin>>n;
    for(i=0;i<n;i++)
        cin>>a[i];
    sort(a,a+n);
    for(i=n-1;i>=0;i--)
    {
        if(a[i]==a[i-1])
        {c++;
        s*=a[i];
        a[i-1]=0;}
        if(c==2) break;
    }
    if(c>=2) cout<<s<<endl;
    else cout<<'0'<<endl;
}