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 <vector>
#include <algorithm>
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());
	
	vector<int> cand;
	for(int i=0; i<n-1; i++){
		if(a[i]==a[i+1]){
			cand.push_back(a[i]);
			i++;
		}
	}
	if((int)cand.size() < 2){
		cout << 0 << endl;
	}else{
		cout << (long long int)cand.back() * cand[cand.size()-2] << endl;
	}
	return 0;
}