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>
using namespace std;


int main(){
	int n;
	scanf("%d", &n);
	int a[n];
	for(int i = 0; i < n; i++){
		scanf("%d", &a[i]);
	}
	sort(a, a+n);
	int i;
	long w = 0, h = 0;
	for(i = n - 1; i > 0; i--){
		if(a[i] == a[i-1]){
			w = a[i];
			i = i-2;
			break;
		}
	}
	for( ; i > 0; i--){
		if(a[i] == a[i-1]){
			h = a[i];
			break;
		}
	}
	printf("%ld\n", h*w);
	return 0;
}