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;

long long a[100010];

int main(void){
	int n;
	long long h=0, w=0, ans=0;
	cin >> n;
	for(int i=0; i<n; i++) cin >> a[i];

	sort(a, a+n);
	reverse(a, a+n);

	for(int i=0; i<n; i++){
		if(a[i]==a[i+1]){
			if(h==0) h = a[i];
			else w = a[i];
			i++;
		}
		ans = h*w;
		if(ans>0) break;
	}
	cout << ans << endl;
}