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 <stdio.h>
#include <algorithm>
using namespace std;
int main(void){
  int n,a[100000],i;
  long x,y;
  scanf("%d",&n);
  for (i=0;i<n;i++) scanf("%d",&a[i]);
  std::sort(a,a+n);
  i=n-1;
  while (a[i]!=a[i-1]&&i>=0) i--;
  if (i==0){
    printf("0\n");
    return 0;
  }
  x=a[i];
  i-=2;
  while (a[i]!=a[i-1]&&i>=0) i--;
  if (i==0){
    printf("0\n");
    return 0;
  }
  y=a[i];
  printf("%ld\n",x*y);
  return 0;
}