#include<bits/stdc++.h>
using namespace std;

//* ATCODER
#include<atcoder/all>
using namespace atcoder;
typedef modint998244353 mint;
//*/

/* BOOST MULTIPRECISION
#include<boost/multiprecision/cpp_int.hpp>
using namespace boost::multiprecision;
//*/

typedef long long ll;

#define rep(i, s, n) for (int i = (int)(s); i < (int)(n); i++)
#define rrep(i, s, n) for (int i = (int)(n)-1; i >= (int)(s); i--)

template <typename T> bool chmin(T &a, const T &b) {
	if (a <= b) return false;
	a = b;
	return true;
}

template <typename T> bool chmax(T &a, const T &b) {
	if (a >= b) return false;
	a = b;
	return true;
}

template <typename T> T max(vector<T> &a){
	assert(!a.empty());
	T ret = a[0];
	for (int i=0; i<(int)a.size(); i++) chmax(ret, a[i]);
	return ret;
}

template <typename T> T min(vector<T> &a){
	assert(!a.empty());
	T ret = a[0];
	for (int i=0; i<(int)a.size(); i++) chmin(ret, a[i]);
	return ret;
}

template <typename T> T sum(vector<T> &a){
	T ret = 0;
	for (int i=0; i<(int)a.size(); i++) ret += a[i];
	return ret;
}

// makediv
vector<ll> makediv(ll n){
	vector<ll> ld, ud;
	for (ll i=1; i*i<=n; i++){
		if (n%i == 0){
			ld.push_back(i);
			if (i != n/i){
				ud.push_back(n/i);
			}
		}
	}
	reverse(ud.begin(), ud.end());
	ld.insert(ld.end(), ud.begin(), ud.end());
	return ld;
}
// -----


int main(){
	int n; cin >> n;
	vector<ll> d = makediv(n);
	int m = d.size();
	vector<long double> dp(m);
	for (int i=1; i<m; i++){
		vector<ll> cnts(i);
		long double tr = 0;
		ll z = d[m-1] / d[i];
		for (int j=i-1; j>=0; j--){
			if (d[i] % d[j] != 0) continue;
			cnts[j] = d[m-1] / d[j];
			for (int k=j+1; k<i; k++){
				if (d[k] % d[j] == 0){
					cnts[j] -= cnts[k];
				}
			}
			cnts[j] -= z;
			tr += cnts[j] * dp[j];
		}
		tr += n;
		tr *= 1 / (long double)(n - d[m-1] / d[i]);
		dp[i] = tr;
	}
	cout << fixed << setprecision(15);
	cout << dp[m-1] << endl;
}