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<bits/stdc++.h>
using namespace std;
 
int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);
	int n;
	cin >> n;
	vector<int> v(n);
	for(int i=0;i<n;i++)cin>>v[i];
	sort(v.begin(), v.end());
	long long a = 0, b = 0;
	for(int i = n - 1; i >= 0; i--){
		if(i == 0) break;
		if(v[i] == v[i - 1]){
			if(a == 0) a = v[i];
			else if(b == 0)b = v[i];
			else break;
			i--;
		}
	}
 
	cout << a * b <<endl;
 
	return 0;
}