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<algorithm>
using namespace std;
int a[100010];
int main()
{
    int n;
    long long ans,a1=-2,a2=-2;
    cin>>n;
    for(int i=1;i<=n;i++) cin>>a[i];
    sort(a+1,a+1+n);
    for(int i=n;i>=2;i--) if(a[i]==a[i-1]) {a1=a[i],a[i]=a[i-1]=-1;break;}
    for(int i=n;i>=2;i--) if(a[i]==a[i-1]&&a[i]!=-1) {a2=a[i];break;}
    if(a1!=-2&&a2!=-2) cout<<a1*a2<<endl; else cout<<0<<endl;
    return 0;
}