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(){
	int n,x[100005],a=0;
	long long s[2];
	cin >> n;
	for(int i=0;i<n;i++){
		cin >> x[i];
	}
	sort(x,x+n);
	for(int i=n-1;i>0;i--){
		if(x[i]==x[i-1]){
			a++;
			s[a-1]=x[i];
			i--;
			if(a==2){
				cout << s[0]*s[1] << endl;
				return 0;
			}
		}
	}
	cout << "0" << endl;
	return 0;
}