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.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Main {

    Scanner scanner = new Scanner(System.in);

    public static void main(String[] args) {
        new Main().compute();
    }

    void compute() {
        int N = scanner.nextInt();
        List<Integer> A = new ArrayList<>();
        for (int i = 0; i < N; i++) {
            A.add(scanner.nextInt());
        }
        A.sort((o1, o2) -> o2 - o1);
        int[] max = new int[2];
        max[0] = 0;
        max[1] = 0;
        int twin = 0, prev = -1;
        for (int Ai : A) {
            if (Ai == prev) {
                max[twin] = Ai;
                twin++;
                prev = -1;
                if (twin == 2) {
                    break;
                }
            } else {
                prev = Ai;
            }
        }
        System.out.println((long)max[0] * max[1]);
    }
}
