fn main() {
    let mut n = String::new();
    std::io::stdin().read_line(&mut n).ok();
    let n: usize = n.trim().parse().unwrap();

    let mut dp = vec![vec![0.; 7]; n+1];
    dp[0][0] = 1.;
    for i in 0..n {
        for j in 0..=6 {
            if dp[i][j] == 0. { continue; }
            dp[i+1][j] += j as f64 / 6. * dp[i][j];
            if j < 6 {
                dp[i+1][j+1] += (6 - j) as f64 / 6. * dp[i][j];
            }
        }
    }
    println!("{}", dp[n][6]);
}