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 Java (OpenJDK 11.0.6) (judge verdict: Wrong Answer)

import java.util.Scanner;
 
public class Main {
 
	static int ans;
 
	public static void main(String[] args) {
 
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		long m = 1000000000 * 1000000000;
		ans = 0;
		double[] a = new double[n];
		for(int i =0; i<n;i++) {
			a[i] = sc.nextDouble();
			a[i] = a[i] * 1000;
//			System.out.println(a[i]);
		}
		for(int i = 0; i < (a.length-1);i++) {
			for(int j = i+1; j < a.length;j++) {
				double variable = a[i] * a[j];
				variable = variable / 1000000;
//				long a_i = (long) (a[i] * 1000000000);
//				long a_j = (long) (a[i] * 1000000000);
//				long variables = a_i * a_j;
//				double variable = (double)variables / m;
				if ((variable == Math.floor(variable)) && !Double.isInfinite(variable)) {
				    ans++;
//				    System.out.println(variable);
				}
			}
		}
		
		
		
		System.out.println(ans);
			
	}
	
}