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.*;

public class Main {
	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		final int N = sc.nextInt();
		long ary[] = new long[N];
		
		for(int i = 0; i < N; i++) {
			ary[i] = sc.nextLong();
		}
		
		Arrays.sort(ary);
		
		int cnt = 0;
		long sideLength1 = 0;
		long sideLength2 = 0;
		
		for(int i = N - 1; i > 0; i--) {
			if(ary[i] == ary[i - 1] && cnt == 0) {
				sideLength1 = ary[i];
				cnt++;
				i--;
				continue;
			}
			
			if(ary[i] == ary[i - 1] && cnt == 1) {
				sideLength2 = ary[i];
				cnt++;
				i--;
			}
			
			if(cnt >= 2) {
				System.out.println(sideLength1 * sideLength2);
				return;
			}
		}
		System.out.println(0);
	}
}
