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;
	vector<int> a(n);	for(int i=0;i<n;i++) cin>>a[i];
	sort(a.begin(), a.end());

	long long b[2];	 b[0]=b[1]=0;
	int p=0;

	int i=n-1;
	while(i-1>=0){
		if(a[i]==a[i-1]){
			b[p]=a[i];
			++p;

			if(p>=2) break;
			else{
				i-=2;
				continue;
			}
		}else{
			i--;
		}
	}


	long long ans=b[0]*b[1];
	cout<<ans<<endl;

	return 0;
}
