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::str::FromStr;
use std::fmt::Debug;
use std::cmp;

#[allow(dead_code)]
fn read_as_vec<T>() -> Vec<T>
where T: FromStr, <T as FromStr>::Err : Debug{
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).unwrap();
    s.trim().split_whitespace().map(|c| T::from_str(c).unwrap()).collect()

}

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

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

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

fn num_of_anti(n: u64, c: u64, d: u64) -> u64{
    n - (n/c + n/d - n/lcm(c, d))
}

fn main(){
    let line: Vec<u64> = read_as_vec();
    let (a, b, c, d) = (line[0], line[1], line[2], line[3]);

    let ans = num_of_anti(b, c, d) - num_of_anti(a-1, c, d);
    
    println!("{}", ans);
}