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<long long> a(n) ;
	for(auto &i:a) cin >> i ;
	sort(a.begin(),a.end()) ;
	long long l,m ;
	l = m = 0 ;
	for(int i=n-1;i>0;i--){
		if(a.at(i)==a.at(i-1)){
			if(l==0) l = a.at(i) ;
			else{
				m = a.at(i) ;
				break ;
			}
			i-- ;
		}
	}
	cout << l*m << endl ;
}
