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::FromStr;

fn input_u64_tuple() -> (u64, u64, u64, u64) {
    let mut line: String = String::new();
    io::stdin().read_line(&mut line);
    let vec: Vec<u64> = line.split_whitespace().map(|s| s.parse().unwrap()).collect();
    (vec[0], vec[1], vec[2], vec[3])
}

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

fn calc(n: u64, c: u64, d: u64) -> u64 {
    n - n/c - n/d + n/(c*d/gcd(c, d))
}

fn main() {
    let (a, b, c, d) = input_u64_tuple();
    println!("{}", calc(b, c, d) - calc(a - 1, c, d));
}