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 a[100010];

int main(){
	int n;
	scanf("%d", &n);
	for(int i = 0; i < n; i++)
		scanf("%d", a + i);
	sort(a, a + n);
	long ans = -1;
	bool flag = false;
	int now, pre = a[n-1];
	for(int i = n - 2; i >= 0; i--) {
		now = a[i];
		if(pre == now) {
			ans *= now;
			if(flag) break;
			flag = true;
			i--;
			pre = a[i];
		}else{
			pre = now;
		}
	}
	printf("%ld\n", (ans == -1) ? 0 : -ans);
}
