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;
#define AC ios_base::sync_with_stdio(0),cin.tie(0);
int main(void)
{
	AC;
	long long int x[100005];
	set<long long> s;
	priority_queue<long long int> pq;
	int T,n,i;
	long long a;
	cin>>n;
	for(i=0;i<n;i++){
		cin>>a;
		if(s.count(a)) pq.push(a), s.erase(a);
		else s.insert(a);
	}
	if(pq.size()>=2){
		a=pq.top();
		pq.pop();
		cout<<pq.top()*a<<"\n";
	}
	else cout<<0<<"\n";
}


