#![allow(non_snake_case)]

use std::io::{ self, prelude::* };

macro_rules! pick {
    ($tokens:expr) => {
        $tokens.next().unwrap().parse().expect("parse error")
    }
}

fn gcd(a: i64, b: i64) -> i64 {
    if b == 0 {
        a
    }
    else {
        gcd(b, a%b)
    }
}

fn main() {
    let mut s = String::new();
    io::stdin().read_to_string(&mut s).expect("i/o error");
    let mut tokens = s.split_whitespace();

    let N: i64 = pick!(tokens);
    let D: i64 = pick!(tokens);

    let ans = N/gcd(N,D) - 1;

    println!("{}", ans);
}