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# (.NET Core 3.1.201) (judge verdict: Time Limit Exceeded)

using System;
using System.Linq;

class Program
{
	static void Main(string[] args)
	{
		int N = int.Parse(Console.ReadLine());
		double[] vs = new double[N]; // double型の配列の宣言
		for (int i = 0; i < N; i++)
		{
			vs[i] = Convert.ToDouble(Console.ReadLine());
		}
		int count = 0;
		int b = 0;
		for (int i = 0; i < N - 1; i = i + 0)
        {
			int a = i + 1 + b;
			if ((vs[i] * vs[a]) % 1 == 0.000000000000000000000 && vs[i] != vs[a]) { count++; }
			b++;
			if(a == N - 1) { b = 0; i++; }
        }
		Console.WriteLine(count);
	}
}