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 k[100005];
int main(){
	int n;
	scanf("%d",&n);
	for(int i=0;i<n;i++){
		scanf("%d", &k[i]);
	}
	sort(k,k+n);
	long long int a=0,b=0;
	for(int i=n-1;i>0;i--){
		if(k[i]==k[i-1]){
			if(a==0){
				a=k[i];
				i--;
			}else{
				b=k[i];
				break;
			}
		}
	}
	long long int sum=a*b;
	cout<<a*b<<endl;
	return 0;
}