#include <bits/stdc++.h>
using namespace std;
using std::cout;
using std::cin;
using std::endl;
using ll=long long;
using ld=long double;
const ll ILL=2167167167167167167;
const int INF=2100000000;
const int mod=998244353;
#define rep(i,a,b) for (int i=(int)(a);i<(int)(b);i++)
#define all(p) p.begin(),p.end()
template<class T> using _pq = priority_queue<T, vector<T>, greater<T>>;
template<class T> ll LB(vector<T> &v,T a){return lower_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> ll UB(vector<T> &v,T a){return upper_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> bool chmin(T &a,T b){if(a>b){a=b;return 1;}else return 0;}
template<class T> bool chmax(T &a,T b){if(a<b){a=b;return 1;}else return 0;}
template<class T> void So(vector<T> &v) {sort(v.begin(),v.end());}
template<class T> void Sore(vector<T> &v) {sort(v.begin(),v.end(),[](T x,T y){return x>y;});}
bool yneos(bool a,bool upp=0){if(a){cout<<(upp?"YES\n":"Yes\n");}else{cout<<(upp?"NO\n":"No\n");}return a;}
template<class T> void vec_out(vector<T> &p,int ty=0){
if(ty==2){cout<<'{';for(int i=0;i<(int)p.size();i++){if(i){cout<<",";}cout<<'"'<<p[i]<<'"';}cout<<"}\n";}
else{if(ty==1){cout<<p.size()<<"\n";}for(int i=0;i<(int)(p.size());i++){if(i) cout<<" ";cout<<p[i];}cout<<"\n";}}
template<class T> T vec_min(vector<T> &a){assert(!a.empty());T ans=a[0];for(auto &x:a) chmin(ans,x);return ans;}
template<class T> T vec_max(vector<T> &a){assert(!a.empty());T ans=a[0];for(auto &x:a) chmax(ans,x);return ans;}
template<class T> T vec_sum(vector<T> &a){T ans=T(0);for(auto &x:a) ans+=x;return ans;}
int pop_count(long long a){int res=0;while(a){res+=(a&1),a>>=1;}return res;}
template<class T> bool inside(T l,T x,T r){return l<=x&&x<r;}


//Nの正の約数を列挙する
vector<long long> Divisors(long long N){
    vector<long long> p,q;
    long long i=1,K=0;
    while(i*i<N){
        if(N%i==0){
            p.push_back(i);
            q.push_back(N/i);
            K++;
        }
        i++;
    }
    if(i*i==N) p.push_back(i);
    for(int i=K-1;i>=0;i--){
        p.push_back(q[i]);
    }
    return p;
}

void solve();
// CYAN / FREDERIC
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    
    int t = 1;
    // cin >> t;
    rep(i, 0, t) solve();
}

void solve(){
    ll N;
    cin >> N;
    auto D = Divisors(N);
    int L = D.size();
    vector<ld> dp1(L), dp2(L);
    vector<ll> C(L);
    rep(i, 0, L) C[i] = N / D[i];
    for (int i = L - 1; i >= 0; i--){
        rep(j, i + 1, L) if (D[j] % D[i] == 0){
            C[i] -= C[j];
        }
    }
    map<ll, int> m;
    for (auto x : D) m[x] = m.size();
    dp2[L - 1] = 1;
    for (int i = L - 1; i > 0; i--){
        vector<ll> p(L);
        rep(j, 0, L) p[m[gcd(D[j], D[i])]] += C[j];
        dp1[i] += dp2[i] * ((ld)(N) / (ld)(N - p[i]));
        rep(j, 0, i){
            ld pro = (ld)(p[j]) / (ld)(N - p[i]);
            dp1[j] += dp1[i] * pro;
            dp2[j] += dp2[i] * pro;
        }
    }
    cout << fixed << setprecision(20) << dp1[0] << "\n";
}