fn getline() -> String{
        let mut __ret=String::new();
        std::io::stdin().read_line(&mut __ret).ok();
        return __ret;
}

fn main(){
        let ab : Vec<i64> = getline().trim().split(' ').map(|x| x.parse().unwrap()).collect();
        if ab[0] < ab[1] {
                println!("{}", ab[1] - 2);
        } else {
                println!("{}", 2000000000 - ab[1] - 1);
        }
}