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: Wrong Answer)

use std::io::*;
use std::str::FromStr;
use std::collections::HashSet;

fn read<T: FromStr>() -> T {
    let stdin = stdin();
    let stdin = stdin.lock();
    let token: String = stdin
        .bytes()
        .map(|c| c.expect("failed to read char") as char)
        .skip_while(|c| c.is_whitespace())
        .take_while(|c| !c.is_whitespace())
        .collect();
    token.parse().ok().expect("failed to parse token")
}

fn main() {
    let a: u64 = read();
    let b: u64 = read();
    let c: u64 = read();
    let d: u64 = read();
    let mut set = HashSet::new();
    let all_count = b - a + 1;
    let c_count = (b / c) - (a / c);
    let d_count = (b / d) - (a / d);
    for i in (a / c) - 1..(b / c) + 2 {
        set.insert(i * c);
    }
    for i in (a / d) - 1..(b / d) + 2 {
        set.insert(i * d);
    }
    let mut minus = 0;
    for i in set {
        if a <= i && i <= b {
            minus += 1;
        }
    }
    println!("{}", all_count - minus);
}