#include <bits/stdc++.h>
#define _ ios_base::sync_with_stdio(0);cin.tie(0);
using namespace std;
int main(){
	int num;
	cin>>num;
	long long int a[num];
	for(int i=0;i<num;i++){
		cin>>a[i];
	}
	sort(a,a+num);
	long long int s1=0,s2=0;
	for(int i=num-2;i>=0;i--){
		if(a[i]==a[i+1]){
			if(s1==0){
				s1=a[i];	
			}
			else{
				s2=a[i];
				break;
			}
			a[i]=0;
			a[i+1]=0;
		}
	}
	cout<<s1*s2<<endl;
}

### Prompt

Create a solution in Cpp for the following problem:

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

### Response

```cpp
#include <bits/stdc++.h>
#define _ ios_base::sync_with_stdio(0);cin.tie(0);
using namespace std;
int main(){
	int num;
	cin>>num;
	long long int a[num];
	for(int i=0;i<num;i++){
		cin>>a[i];
	}
	sort(a,a+num);
	long long int s1=0,s2=0;
	for(int i=num-2;i>=0;i--){
		if(a[i]==a[i+1]){
			if(s1==0){
				s1=a[i];	
			}
			else{
				s2=a[i];
				break;
			}
			a[i]=0;
			a[i+1]=0;
		}
	}
	cout<<s1*s2<<endl;
}

```