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 n,s,k,mx,fs,sc,i,t[1000005];
long long e,e1;


int main() 
{
    cin>>n;
    for (i=1; i<=n; i++)
        cin>>t[i];
    sort(t+1,t+n+1);
    for (i=n; i>1 && (!e || !e1); i--)
        if (t[i]==t[i-1])
        {
            if (!e) e=t[i],i--; else e1=t[i],i--;
        }
    cout<<e*e1;
}