use proconio::input;
use std::collections::HashMap;

fn gcd(x: usize, y: usize) -> usize {
	if x < y {
		return gcd(y, x);
	}
	if y == 0 {
		return y;
	}
	gcd(y, x % y)
}

fn main() {
	input! {
		N: usize,
	}
	
	let mut dp = HashMap::new();
	fn rec(dp: &mut HashMap<usize, f64>, n: usize) -> f64 {
		if n == 0 {
			return 0.0;
		}
		if let Some(&ans) = dp.get(&n) {
			return ans;
		}
		let mut sum = 0.0;
		for i in 1 ..= n {
			sum += 1.0 + rec(dp, gcd(n, i));
		}
		let ans = sum / n as f64;
		dp.insert(n, ans);
		ans
	}
	
	println!("{}", rec(&mut dp, N));
}