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 <vector>
#include <algorithm>
using namespace std;

const int MAX_N=100000;
int n,a[MAX_N]={};

int main(){
	cin >> n;
	for(int i=0;i<n;i++){
		cin >> a[i];
	}
	
	long long int sum=1,t=0;
	sort(a,a+n);
	for(int i=0;i<n-1;i++){
		if(a[(n-1)-i]==a[(n-1)-(i+1)]){
			sum*=a[(n-1)-i];
			i++;
			t++;
		}
		if(t==2) break;
	}
	cout << (t==2?sum:0) << endl;
	return 0;
}
