Problem:
Score : 300 points

Problem Statement

You are given four integers A, B, C, and D. Find the number of integers between A and B (inclusive) that can be evenly divided by neither C nor D.

Constraints

1\leq A\leq B\leq 10^{18}

1\leq C,D\leq 10^9

All values in input are integers.

Input

Input is given from Standard Input in the following format:

A B C D

Output

Print the number of integers between A and B (inclusive) that can be evenly divided by neither C nor D.

Sample Input 1

4 9 2 3

Sample Output 1

2

5 and 7 satisfy the condition.

Sample Input 2

10 40 6 8

Sample Output 2

23

Sample Input 3

314159265358979323 846264338327950288 419716939 937510582

Sample Output 3

532105071133627368

Solution in Rust (1.42.0) (judge verdict: Accepted)

use whiteread::parse_line;
use num_integer::gcd;

fn main() {
    let (a, b, c, d): (usize, usize, usize, usize) = parse_line().unwrap();
    let cd: usize = c*d / gcd(c, d);

    let bc = b/c;
    let ac = (a-1)/c;
    let bd = b/d;
    let ad = (a-1)/d;
    let bcd = b/cd;
    let acd = (a-1)/cd;

    let cc = bc - ac;
    let dc = bd - ad;
    let cdc = bcd - acd;

    println!("{}", b - a + 1 - cc - dc + cdc);
}