use std::io::*; use std::str::*; use std::fmt::*; fn readw<T: FromStr, R: Read>(s: &mut R) -> Option<T> { let s = s.bytes().map(|c| c.unwrap() as char) .skip_while(|c| c.is_whitespace()) .take_while(|c| !c.is_whitespace()) .collect::<String>(); if s.is_empty() { None } else { s.parse::<T>().ok() } } fn read<T: FromStr, R: Read>(s: &mut R) -> T { readw(s).unwrap() } #[allow(dead_code)] fn p<A: Display>(a: &A) { println!("{}", a); } #[allow(dead_code)] fn p2<A: Display, B: Display>(a: &A, b: &B) { println!("{} {}", a, b); } #[allow(dead_code)] fn p3<A: Display, B: Display, C: Display>(a: &A, b: &B, c: &C) { println!("{} {} {}", a, b, c); } fn main(){ let s = stdin(); let mut s = BufReader::new(s.lock()); let s = &mut s; while let Some(m) = readw(s) { let n = read(s); println!("{:.10}", (0..n).fold(m, |e: f64, _| (e * 2.0 + e + 1.0) / 3.0)); } }