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
#include <bits/stdc++.h>
using namespace std;

int main() {
  int N;
  cin >> N;
  vector<int> A(N);
  for (int& a : A) cin >> a;
  sort(A.begin(), A.end(), greater<int>());
  long i = 0, x = 0, y = 0;
  while (i < N-1) {
    if (A[i] == A[i+1]) {
      if (x == 0) x = A[i];
      else {
        y = A[i];
        break;
      }
      i += 2;
    } else {
      i++;
    }
  }
  cout << x * y << endl;
}