#![allow(unused_imports)]
#![allow(non_snake_case)]
use std::collections::HashMap;
use std::collections::HashSet;
use std::collections::VecDeque;

#[allow(unused_macros)]
macro_rules! read {
    ([$t:ty] ; $n:expr) =>
        ((0..$n).map(|_| read!([$t])).collect::<Vec<_>>());
    ($($t:ty),+ ; $n:expr) =>
        ((0..$n).map(|_| read!($($t),+)).collect::<Vec<_>>());
    ([$t:ty]) =>
        (rl().split_whitespace().map(|w| w.parse().unwrap()).collect::<Vec<$t>>());
    ($t:ty) =>
        (rl().parse::<$t>().unwrap());
    ($($t:ty),*) => {{
        let buf = rl();
        let mut w = buf.split_whitespace();
        ($(w.next().unwrap().parse::<$t>().unwrap()),*)
    }};
}

#[allow(dead_code)]
fn rl() -> String {
    let mut buf = String::new();
    std::io::stdin().read_line(&mut buf).unwrap();
    buf.trim_end().to_owned()
}

fn main() {
    let k = read!(usize);
    let mut table = vec![0u64; k + 6];
    let mut b = 1;
    for i in (0..=k - 1).rev() {
        table[i] = table[i+1] + 6*table[i+2] + 6*6*table[i+3] + 6*6*6*table[i+4] + 6*6*6*6*table[i+5] + 6*6*6*6*6*table[i+6] + b;
        b *= 6;
    }
    println!("{}", table[0] as f64 / (b/6) as f64);
}