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(void) {
  long long N;
  cin >> N;
  vector<long long> A(N);
  for (int i = 0; i < N; i++) {
    cin >> A[i];
  }
  sort(A.begin(), A.end(), greater<int>());
  long long ans = 1;
  int cnt = 0;
  for (int i = 1; i < N; i++) {
    if (cnt >= 2) break;
    if (A[i] == A[i - 1]) {
      ans *= A[i];
      cnt++;
      i++;
    }
  }

  cout << (cnt != 2 ? 0 : ans) << endl;
  return 0;
}