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<algorithm>
#define int long long
using namespace std;

int n,a[100000],x1,x2;

signed main(){
	cin>>n;
	for(int i=0;i<n;i++){
		cin>>a[i];
	}
	sort(a,a+n);
	for(int i=n-1;i>=1;i--){
		if(a[i]==a[i-1]){
			if(x1!=0&&x2==0) x2=a[i];
			if(x1==0) x1=a[i];
			i--;
		}
	}
	int s=x1*x2;
	cout<<s<<endl;
	return 0;
}