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>
#define IOS ios_base::sync_with_stdio(false); cin.tie(0);
using namespace std;

int main(){
//	IOS;
	int n,inp;
	cin >> n;
	map<int,int> num;
	vector<int> can;
	for(int i=0;i<n;i++){
		cin >> inp;
		num[inp]++;
		if(num[inp]%2==0) can.push_back(inp);
	}
	sort(can.begin(),can.end(),greater<int>());
	if(can.size()<2) cout << "0\n";
	else cout << (long long int)can[0]*can[1] << '\n';
	return 0;
}
