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;
typedef long long ll;
int main(){ 
	vector<ll>a;
	map<ll,ll>l;
	int n;
	cin >> n;
	ll len;
	for (int i =0;i<n;i++)
	{
		cin >> len;
		l[len]++;
		if(l[len]==2)
			{
				a.push_back(len);
			}
		else if (l[len]==4)
		{
			a.push_back(len);
		}
	}
	sort(a.begin(),a.end());
	if (a.size()<=1){
		cout<<"0";
	}
	else {
		cout<< a[a.size()-1]*a[a.size()-2];
	}
	return 0;
}