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);
    int n = sc.nextInt();
    HashMap<Long, Integer> map = new HashMap<Long, Integer>();
    for(int i = 0; i < n; i++) {
      long a = sc.nextLong();
      if(map.containsKey(a)) {
        map.put(a, map.get(a) + 1);
      } else {
        map.put(a, 1);
      }
    }
    ArrayList<Long> list = new ArrayList<Long>();
    long ans = 0;
    for(long key : map.keySet()) {
      int t = map.get(key);
      while(t > 1) {
        list.add(key);
        t -= 2;
      }
    }
    Collections.sort(list);
    if(list.size() > 1) {
      ans = (list.get(list.size() - 1)) * (list.get(list.size() - 2));
    }
    System.out.println(ans);
  }
}