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;
const long long N=100005;
long long n;
long long a[N];
long long cnt[3],tot=0;
int main(){
    scanf("%lld",&n);
    for(long long i=1;i<=n;i++)scanf("%lld",&a[i]);
    sort(a+1,a+n+1);
    for(long long i=n;i>=1;i--)if(a[i]==a[i-1]){cnt[++tot]=a[i];i--;if(tot==2)break;}
    printf("%lld\n",cnt[1]*cnt[2]);
    return 0;
}