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 (GCC 9.2.1) (judge verdict: Wrong Answer)

#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <stdbool.h>

#define MAX 200000

int main(){
    int num = 0;
    scanf("%d", &num);
    long double array[MAX] = {0};

    for(int i = 0; i < num; i++) {
        scanf("%Lf", &(array[i]));

    }

    int pairs = 0;

    for(int i = 0; i < num -1; i++){
        for(int j = i + 1; j < num; j++){
            if((roundf(array[i]*array[j]) == array[i]*array[j])) {
                pairs++;
                //printf("%Lf x %Lf = %Lf\n", array[i], array[j], array[i]*array[j]);
            }
            
        }
    }

    printf("%d\n", pairs);

}