const fn gcd(a: u64, b: u64) -> u64 {
    let mut x = (a, b);
    while x.1 > 0 {
        x = (x.1, x.0 % x.1);
    }
    x.0
}

fn main() {
    let mut xx = String::new();
    std::io::stdin().read_line(&mut xx).ok();
    let xx: Vec<u64> = xx.split_whitespace().flat_map(str::parse).collect();

    println!("{}", xx[0] / gcd(xx[0], xx[1]) - 1);
}