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 <functional>
using namespace std;
long long ans=1,cnt;
int n,a[100005],j;
int main(){
    cin>>n;
    for(int i=0;i<n;i++)cin>>a[i];
    sort(a,a+n,greater<int>());
    for(int i=0;i<n-1;i++){
        if(a[i]==a[i+1]){
            j++;
          	i++;
            ans*=a[i];
        }
        if(j==2)break;
    }
    cout<<(j==2?ans:0)<<endl;
}