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)

// Try AtCoder
// author: Leonardone @ NEETSDKASU

fn main() {
    let mut stdin = String::new();
    std::io::Read::read_to_string(
        &mut std::io::stdin(),
        &mut stdin).unwrap();
    let mut stdin = stdin.split_whitespace();
    let mut get = || stdin.next().unwrap();
    macro_rules! get {
        ($t:ty) => (get().parse::<$t>().unwrap());
        () => (get!(i64));
    }
    
    let a = get!();
    let b = get!();
    let c = get!();
    let d = get!();
    let cd = c / gcd(c, d) * d;
    let fc = if a % c == 0 { 1 } else { 0 };
    let fd = if a % d == 0 { 1 } else { 0 };
    let fcd = if a % cd == 0 { 1 } else { 0 };
    let mut ans = b - a + 1;
    ans -= b / c - (a - fc) / c;
    ans -= b / d - (a - fd) / d;
    ans += b / cd - (a - fcd) / cd;
    
    println!("{}", ans);
}

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