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<long long> A(N);
	for(auto &i:A)cin >> i;
	
	sort(A.begin(),A.end());
	reverse(A.begin(),A.end());
	
	long long a=0,b=0;
	for(int i=0;i<N-1;i++){
		if(A[i]==A[i+1]){
			if(a==0)a=A[i];
			else if(b==0)b=A[i];
			i++;
		}
	}
	cout << a*b << endl;
	return 0;
}