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<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
using namespace std; 
int main(){
	int n,i;
	cin>>n;
	int a[100005];
	a[0]=0;
	long long x=0,y=0;
	for(i=1;i<=n;i++){
		cin>>a[i];
	}
	sort(a+1,a+(n+1));
	for(i=n;i>=1;i--){
		if(a[i]==a[i-1]){
			x=a[i];
			break;
		}
	}
	for(int j=i-2;j>=1;j--){
		if(a[j]==a[j-1]){
			y=a[j];
			break;
		}
	}
	cout<<x*y<<endl;
	return 0;
}