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 java.io.*;
import java.math.*;
public class Main{
    public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		PrintWriter ou = new PrintWriter(System.out);
		int n = Integer.parseInt(sc.next());
		int[] a = new int[n];
		for(int i = 0 ; i < n ; i++) a[i] = Integer.parseInt(sc.next());
		sc.close();
		Arrays.sort(a);
		long aa = 0 , bb = 0;
		int now = n - 1;
		while(now > 0 && a[now] != a[now - 1]) now--;
		aa = a[now];
		now -= 2;
		if(now == 0) ou.println(0);
		else{
			while(now > 0 && a[now] != a[now - 1]) now--;
			if(now >= 0) bb = a[now];
			ou.println(aa * bb);
		}
		ou.flush();
	}
}