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;
int main(){
	int i,n;
	long long c,d,e;
	cin >> n;
	vector<long long> a(n+4);
	for(i=0;i<n;i++){
		cin >> a[i];
	}
	sort(a.begin(),a.end());
	for(i=0;i<n+3;i++){
		if(a[n+3-i]==a[n+2-i]){
			c = a[n+3-i];
			d = i;
			break;
		}
	}
	for(i=0;i<n+1-d;i++){
		if(a[n+1-d-i]==a[n-d-i]){
			e = a[n+1-d-i];
			break;
		}
	}
	cout << c*e << endl;
}
	
	