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)

fn gcd(a:i64, b:i64) -> i64 {
    if a > b {
        gcd(b, a);
    }
    return if a == 0 { b } else { gcd(b % a, a) };
}

fn lcm(a:i64, b:i64) -> i64 {
    a * b / gcd(a,b)
}

fn read_vec<T: std::str::FromStr>() -> Vec<T> {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().split_whitespace()
        .map(|e| e.parse().ok().unwrap()).collect()
}

fn num_of_not_multiple(n: i64, c:i64, d:i64) -> i64 {
    let common_multiple = lcm(c, d);
    n - (n / c) - (n / d) + (n / common_multiple)
}

fn main() {
    let input_vec = read_vec::<i64>();
    let a = input_vec[0];
    let b = input_vec[1];
    let c = input_vec[2];
    let d = input_vec[3];
    println!("{}", num_of_not_multiple(b, c, d) - num_of_not_multiple(a-1, c, d));
}