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();
    TreeMap<Long, Integer> map = new TreeMap<>();
    for (int i = 0; i < N; i++) {
      long tmp = sc.nextLong();
      if (map.containsKey(tmp)) {
        map.put(tmp, map.get(tmp) + 1);
      } else {
        map.put(tmp, 1);
      }
    }
    ArrayList<Long> r = new ArrayList<>();
    ArrayList<Long> s = new ArrayList<>();
    Set<Long> keySet = map.keySet();
    for (Long key : keySet) {
      if (map.get(key) >= 2) {
        r.add(key);
      }
      if (map.get(key) >= 4) {
        s.add(key);
      }
    }
    long max1 = 0;
    if (r.size() >= 2) {
      max1 = r.get(r.size() - 1) * r.get(r.size() - 2);
    }
    long max2 = 0;
    if (s.size() >= 1) {
      max2 = s.get(s.size() - 1) * s.get(s.size() - 1);
    }
    System.out.println(Long.max(max1, max2));
  }
}