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;
int main(void){
    long long a[100001],n;
    cin >> n;
    for(int i =0;i<n;i++) cin >> a[i];
    sort(a,a+n,greater<int>());
    long long c=0,d=0,i=0;
    while(!c && i<n){
        if(a[i] == a[i + 1]) {
            c = a[i];
            i++;
        }
        i++;
    }
    while(!d && i<n){
        if(a[i] == a[i+1]) d = a[i];
        i++;
    }
    cout<<c*d;
}