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()
{
	int n;
	cin>>n;
	map<int,int> hm;
	vector<int> ans;
	for(int i=0;i<n;i++)
	{
		int a;
		cin>>a;
		hm[a]++;
		if(hm[a]==2)
		{
			ans.push_back(a);
			hm[a] = 0;
		}
	}
	sort(ans.begin(),ans.end());
	if(ans.size()<2) cout<<0;
	else
		cout<<1LL*ans[ans.size()-1]*ans[ans.size()-2];
	return 0;
}