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[100050];
int main(){
	int n;
	cin>>n;
	for(int i=0;i<n;i++)cin>>a[i];
	sort(a,a+n);
	int k=-1;
	int num=0;
	int p=0,q=0;
	for(int i=n-1;i>=0;i--){
		if(a[i]==k)num++;
		if(num==2){
			num=0;
			if(p==0)p=k;
			else if(q==0){
				q=k;
				break;
			}
			k=0;
		}
		else{
			num=1;
			k=a[i];
		}
	}
	long long ans=((long long)p)*(long long)q;
	cout<<ans<<endl;
	return 0;
}