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<stdio.h>
#include<iostream>
#include<algorithm>
using namespace std;
int main(void)
{
	long long int n,A[100001],i,a,b;
	scanf("%lld",&n);
	for(i=0;i<n;i++) scanf("%lld",&A[i]);
	sort(A,A+n,greater<int>());
	a=0; b=0;
	for(i=0;i<n;i++){
		if(a==0){
			if(A[i]==A[i+1]){
				a=A[i]; i++;
			}
		}
		else{
			if(A[i]==A[i+1]){
				b=A[i];
				break;
			}
		}
	}
	if(b==0) printf("0\n");
	else printf("%lld\n",a*b);
	return 0;
}