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;
long long a[100010],n,sisi1,sisi2;
int main() {
cin>>n;
for(int i=1;i<=n;i++) {
	cin>>a[i];
}
sort(a+1,a+n+1);
for(int i=n;i>=2;i--) {
	if(a[i]==a[i-1]) {
		sisi1=i;
		break;
	}
}
for(int i=sisi1-2;i>=2;i--) {
	if(a[i]==a[i-1]) {
		sisi2=i;
		break;
	}
}
cout<<a[sisi1]*a[sisi2]<<endl;
}