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 (1.42.0) (judge verdict: Accepted)

use proconio::input;

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

fn lcm(a: isize, b:isize) -> isize {
  a * b / gcv(a, b)
}

fn main() {
  input! {
    a: isize,
    b: isize,
    c: isize,
    d: isize
  }
  
  let a = a - 1;
  let common = lcm(c, d);
  let result = b - (b/c + b/d - b/common) - (a - (a/c + a/d - a/common));
  println!("{}", result);
}