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