fn main() {
    let bugget: u32 = read();
    let child: u32 = read();
    let ans = ((bugget/1000) / child) * 1000;
    
    println!("{}", ans);
}


fn read<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().parse().ok().unwrap()
}