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,a,ans[2],i,ch;
map<long long,long long> m;
int main()
{
    scanf("%lld",&n);
    for(i=0;i<n;i++)
    {
        scanf("%lld",&a);
        m[a]++;
        if(m[a]%2==0 && a>ans[ch])
        {
            ans[ch]=a;
            if(ans[0]>ans[1]) ch=1;
            else ch=0;
        }
    }
    printf("%lld",ans[0]*ans[1]);
}
