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(){
    long long N, ans=0, tate=0, yoko=0;
    cin >> N;	
    vector<long long> a(N);
    for(int i=0; i<N; i++){
	cin >> a[i];
    }
    sort(a.begin(), a.end(), greater<long long>());

    for(int i=0; i<N-1; i++){
	if(a[i] == a[i+1]){
	    if(tate == 0){
		tate = a[i];
		i++;
	    }else{
		yoko =a[i];
		break;
	    }
	}
    }

    cout << tate*yoko << endl;

}

