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 <algorithm>
using namespace std;
int main(){
	
	long long int n,l[100000],t=0,y=0,b=0,b2=0,bf;
	cin>>n;
	for(int i=0;i<n;i++){
		cin>>l[i];
	}
	sort(l,l+n);
	for(long long int i=n-1;i>0;i--){
		if(l[i]==l[i-1] && b==0){
			t=l[i];
			bf=i-1;
			b=1;
		}
		if(l[i]==l[i-1] && bf>i && b2==0){
			y=l[i];
			b2=1;
            break;
		}
	}
	cout<<t*y<<endl;
	return 0;
}
