Problem:
Score : 300 points

Problem Statement

You are given N real values A_1, A_2, \ldots, A_N.
Compute the number of pairs of indices (i, j)
such that i < j and the product A_i \cdot A_j is integer.

Constraints

2 \leq N \leq 200\,000

0 < A_i < 10^4

A_i is given with at most 9 digits after the decimal.

Input

Input is given from Standard Input in the following format.

N
A_1
A_2
\vdots
A_N

Output

Print the number of pairs with integer product A_i \cdot A_j (and i < j).

Sample Input 1

5
7.5
2.4
17.000000001
17
16.000000000

Sample Output 1

3

There are 3 pairs with integer product:

7.5 \cdot 2.4 = 18

7.5 \cdot 16 = 120

17 \cdot 16 = 272

Sample Input 2

11
0.9
1
1
1.25
2.30000
5
70
0.000000001
9999.999999999
0.999999999
1.000000001

Sample Output 2

8

Solution in C++ (Clang 10.0.0) (judge verdict: Wrong Answer)

#include <iostream>
#include <vector>

using namespace std;

int main()
{
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);
  
  int n;
  cin >> n;
  
  vector<double> a;
  a.resize(n);
  
  for (auto &f: a)
	cin >> f;  
  
  int c = 0;
  for (int i = 0; i < n; i++)
	for (int j = i; j < n; j++)
		((a[i] * a[j]) == double(int(a[i] * a[j]))) && c++;
  
  cout << c;
  
  return 0;
}