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<map>
#include<vector>
#include<algorithm>
using namespace std;
int main(){
	int n;
	cin >> n;
	map<int,int> m;
	for(int i=0;i<n;i++){
		int a;
		cin >> a;
		m[a]++;
	}
	vector<long long> v;
	for(auto i=m.begin();i!=m.end();i++){
		for(int j=0;j<i->second/2;j++) v.push_back(i->first);
	}
	sort(v.begin(),v.end());
	reverse(v.begin(),v.end());
	if(v.size()<=1) cout << 0 << endl;
	else cout << v[0]*v[1] << endl;
}
