#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf32 1000000001
#define Inf64 1000000000000000001

int main(){
	
	long long n;
	cin>>n;
	vector<long long> y;
	for(long long i=1;i<=n;i++){
		if(n%i==0)y.push_back(i);
	}
	
	vector<long long> c(y.size());
	for(long long i=1;i<=n;i++){
		int g =gcd(i,n);
		c[lower_bound(y.begin(),y.end(),g)-y.begin()]++;
	}
	vector<double> dp(y.size(),0);
	for(int i=1;i<y.size();i++){
		double loop = 0.0;
		rep(j,y.size()){
			int g = gcd(y[i],y[j]);
			if(g==y[i])loop += c[j];
			
		}
		dp[i] += (double)n/(n-loop);
		rep(j,y.size()){
			int g = gcd(y[i],y[j]);
			g = distance(y.begin(),lower_bound(y.begin(),y.end(),g));
			if(g!=i)dp[i] += dp[g] * c[j]/(n-loop);
			
		}
	}
	cout<<fixed<<setprecision(10)<<dp[y.size()-1]<<endl;
		
    return 0;
}