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)

#![allow(non_snake_case)]

fn read_line() -> String {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).unwrap();
    s.trim().to_string()
}

fn read_vec() -> Vec<i64> {
    read_line()
        .split_whitespace()
        .map(|e| e.parse().unwrap())
        .collect()
}

fn read_int_tuple() -> (i64, i64, i64, i64) {
    let v = read_vec();
    (v[0], v[1], v[2], v[3])
}

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

fn main() {
    let (A, B, C, D) = read_int_tuple();
    let lcm = C*D/gcd(C, D);
    let ans = (B-(A-1)) - (B/C-(A-1)/C) - (B/D-(A-1)/D) + (B/lcm-(A-1)/lcm);
    println!("{}", ans);

}