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 get_input() -> String {
    let mut word = String::new();
    std::io::stdin().read_line(&mut word).unwrap();
    word.trim().to_owned()
}


fn lcm(i:i64, j:i64) -> i64 {
  let x = i * j;

  /* 自然数 a > b を確認・入替 */
  let (mut a, mut b) = if i < j { (j, i) } else { (i, j) };

  /* ユークリッドの互除法 */
  let mut r = a % b;
  while r != 0 {
    a = b;
    b = r;
    r = a % b;
  }

  x/b
}

fn main() {
    let line = get_input();
    let mut split = line.split_whitespace();
    let a:i64 = split.next().unwrap().parse().unwrap();
    let b:i64 = split.next().unwrap().parse().unwrap();
    let c:i64 = split.next().unwrap().parse().unwrap();
    let d:i64 = split.next().unwrap().parse().unwrap();

    let l = lcm(c,d);

    let bc = b / c;
    let bd = b / d;
    let bl = b / l;

    let ac = (a-1) / c;
    let ad = (a-1) / d;
    let al = (a-1) / l;

    let ans = (b - bc - bd + bl) - (a-1 - ac - ad + al);
    println!("{}", ans);
}