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<iostream>
#include<unordered_map>
using namespace std;

int main(){
	int n;
	int max1 = 0;
	int max2 = 0;
	unordered_map<int, int> m;
	cin >> n;
	for(int i=0; i<n; i++){
		int tmp;
		cin >> tmp;
		m[tmp]++;
		if(m[tmp]==2){
			if(tmp > max1) {
				max2 = max1;
				max1 = tmp;
			} else if(tmp > max2) max2 = tmp;
		}
	}
	if(m[max1] < 4) {
		cout << (long)max1 * max2;
	} else {
		cout << (long)max1 * max1;
	}
}

