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 (1.15.1) (judge verdict: Accepted)

use std::io::*;
use std::str::*;

fn read<T: FromStr>() -> T {
    let stdin = stdin();
    let s = stdin
        .bytes()
        .map(|c| c.unwrap() as char)
        .skip_while(|c| c.is_whitespace())
        .take_while(|c| !c.is_whitespace())
        .collect::<String>();
    s.parse::<T>().ok().unwrap()
}

fn u64() -> u64 {
    read()
}

fn vec_u64(n: usize) -> Vec<u64> {
    let mut vec = Vec::new();
    for _ in 0..n {
        vec.push(u64())
    }
    vec
}

fn main() {
    let input = vec_u64(4);
    let a = input[0] - 1;
    let b = input[1];
    let c = input[2];
    let d = input[3];

    let lcm = lcm(c, d);
    let aa = (a - a / c) + (a - a / d) - (a - a / lcm);
    let bb = (b - b / c) + (b - b / d) - (b - b / lcm);
    println!("{}", bb - aa);
}

fn lcm(a: u64, b: u64) -> u64 {
    a / gcd(a, b) * b
}

fn gcd(a: u64, b: u64) -> u64 {
    if b > 0 {
        gcd(b, a % b)
    } else {
        a
    }
}