use std::io::{self, Read}; #[derive(Debug)] struct Input { l: i32, k: i32, } fn next_token(cin_lock: &mut io::StdinLock) -> String { cin_lock .by_ref() .bytes() .map(|c| c.unwrap() as char) .skip_while(|c| c.is_whitespace()) .take_while(|c| !c.is_whitespace()) .collect::() } fn read_input(cin_lock: &mut io::StdinLock) -> Input { Input { l: next_token(cin_lock).parse().unwrap(), k: next_token(cin_lock).parse().unwrap(), } } fn solve(input: Input, _cin_lock: &mut io::StdinLock) { let yuu_bites = ((input.l - 1) / 2) / input.k; let answer = yuu_bites * input.k; println!("{}", answer); } fn main() { let cin = io::stdin(); let mut cin_lock = cin.lock(); let input = read_input(&mut cin_lock); solve(input, &mut cin_lock); }