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 <stdio.h>
#include <bits/stdc++.h>
#define mod 1000000007
typedef long long ll;
using namespace std;
int n;
ll s[100005]; 
int main()  
{  
	cin>>n;
	for(int i=0;i<n;i++){
		scanf("%I64d",s+i);
	}
	sort(s,s+n);
	ll ans,k=0;
	for(int i=n-1;i>0;i--){
		if(s[i]==s[i-1]){
			if(k==0){
				ans=s[i];
				i--;k++; 
			}else{
				ans*=s[i];
				cout<<ans<<endl;
				return 0;
			}
		}
	}
	cout<<0<<endl;
	return 0;  
}  
