use std::cmp::*;

fn main(){
    let mut sc = Scanner::new();
    while let Ok(a) = sc.wrapped::<i64>() {
        let b: i64 = sc.next();
        println!("{}", if a < b {
            if a == 1 && b == 2 { 0 }
            else if a+1 == b { a-1 }
            else { (b-a-1) + (a-1) }
        } else {
            if a == 2000000000 { a-b-1 }
            else if a-1==b { 2000000000-a }
            else { (2000000000-a) + (a-b-1) }
        }
        );
    }
}

#[allow(dead_code)]
struct Scanner {
    token_buffer : Vec<String>,
    index : usize,
}

#[allow(dead_code)]
impl Scanner {
    fn new() -> Scanner {
        Scanner { token_buffer: vec![], index: 0 }
    }

    fn wrapped<T>(&mut self) -> Result<T,&str> where T: std::str::FromStr {
        let s = try!(self.fetch_token());
        let t = try!(s.parse::<T>().map_err(|_| "Parse error"));
        Ok(t)
    }
    fn next<T>(&mut self) -> T where T: std::str::FromStr {
        self.wrapped::<T>().unwrap()
    }

    fn fetch_token(&mut self) -> Result<&String,&str> {
        while self.index >= self.token_buffer.len() {
            let mut st = String::new();
            while st.trim() == "" {
                match std::io::stdin().read_line(&mut st) {
                    Ok(l) if l > 0 => continue,
                    Ok(_)  => return Err("End of file"),
                    Err(_) => return Err("Failed to read line"),
                }
            }
            self.token_buffer = st.split_whitespace()
                .map(|x| x.to_string())
                .collect();
            self.index = 0;
        }

        self.index += 1;
        Ok(&self.token_buffer[self.index - 1])
    }
}