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 n;
map<int,int> A;
vector<int> B;

int main(){
	cin >> n;

	for(int i=0;i<n;i++){
		int x;
		cin >> x;
		A[x]++;
		if(A[x]==2){
			B.push_back(x);
			A[x]=0;
		}
	}

	sort(B.begin(),B.end());
	reverse(B.begin(),B.end());

	if(B.size()>1)	cout << (long long)B[0]*B[1] << endl;
	else	cout << 0 << endl;

	return 0;
}