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
import java.util.*;
import static java.lang.System.*;

class Main {
  public static final int MOD = 1000000007;
  public static final int INF = 1000000000;
  public static void main(String[] args) {
    Scanner sc = new Scanner(in);
    int N = sc.nextInt();
    Integer A[] = new Integer[N];
    for(int i=0; i<N; i++) A[i] = sc.nextInt();
    Arrays.sort(A, Comparator.reverseOrder());
    long height = 0;
    long width = 0;
    for(int i=0; i<N-1; i++){
      if(height != 0 && width != 0) break;
      if(A[i].equals(A[i+1])){
        if(height == 0) height = A[i];
        else width = A[i];
        i++;
      }
    }
    long ans = height * width;
    out.println(ans);
  }

  public static int gcd(int a, int b){
    if(b == 0) return a;
    return gcd(b, a%b);
  }
}