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<long long>v;
  for(int i = 0; i < n; ++i) {
    int a;
    cin >> a;
    v.push_back(a);
  }

  sort(v.begin(), v.end());
  long long h = 0, w = 0;
  
  for(int i = 0; i < n - 1; ++i) {
    if(v[i] == v[i + 1]) {
      w = h;
      h = v[i];
      ++i;
    }
  }

  cout << w * h << endl;
  return 0;
}
