#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")

#include <algorithm>
#include <atcoder/all>
#include <bitset>
#include <cassert>
#include <cmath>
#include <ctime>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
using namespace std;
using namespace atcoder;
typedef long long ll;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define repr(i, n) for (int i = (int)(n) - 1; i >= 0; i--)
#define repk(i, k, n) for (int i = k; i < (int)(n); i++)
#define all(v) v.begin(), v.end()
#define mod1 1000000007
#define mod2 998244353
#define mod3 100000007
#define vi vector<int>
#define vs vector<string>
#define vc vector<char>
#define vl vector<ll>
#define vb vector<bool>
#define vvi vector<vector<int>>
#define vvc vector<vector<char>>
#define vvl vector<vector<ll>>
#define vvb vector<vector<bool>>
#define vvvi vector<vector<vector<int>>>
#define vvvl vector<vector<vector<ll>>>
#define pii pair<int, int>
#define pil pair<int, ll>
#define pli pair<ll, int>
#define pll pair<ll, ll>
#define vpii vector<pair<int, int>>
#define vpll vector<pair<ll, ll>>
#define vvpii vector<vector<pair<int, int>>>
#define vvpll vector<vector<pair<ll, ll>>>

using mint = modint998244353;

template <typename T>
void debug(T e) {
    cerr << e << endl;
}

template <typename T>
void debug(vector<T> &v) {
    rep(i, v.size()) { cerr << v[i] << " "; }
    cerr << endl;
}

template <typename T>
void debug(vector<vector<T>> &v) {
    rep(i, v.size()) {
        rep(j, v[i].size()) { cerr << v[i][j] << " "; }
        cerr << endl;
    }
}

template <typename T>
void debug(vector<pair<T, T>> &v) {
    rep(i, v.size()) { cerr << v[i].first << " " << v[i].second << endl; }
}

template <typename T>
void debug(set<T> &st) {
    for (auto itr = st.begin(); itr != st.end(); itr++) {
        cerr << *itr << " ";
    }
    cerr << endl;
}

template <typename T>
void debug(multiset<T> &ms) {
    for (auto itr = ms.begin(); itr != ms.end(); itr++) {
        cerr << *itr << " ";
    }
    cerr << endl;
}

template <typename T>
void debug(map<T, T> &mp) {
    for (auto itr = mp.begin(); itr != mp.end(); itr++) {
        cerr << itr->first << " " << itr->second << endl;
    }
}

void debug_out() { cerr << endl; }

template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
    cerr << H << " ";
    debug_out(T...);
}

int main() {
    ll N;
    cin >> N;
    map<ll, ll> mpdiv;
    for (ll i = 1; i * i <= N; i++) {
        if (N % i == 0) {
            mpdiv[i]++;
            mpdiv[N / i]++;
        }
    }
    vector<ll> divs(0);
    for (auto itr = mpdiv.begin(); itr != mpdiv.end(); itr++) {
        divs.push_back(itr->first);
    }
    sort(all(divs));
    ll len = divs.size();
    // debug(divs);

    vector<double> dp(len);
    dp[0] = 0;

    for (ll i = 1; i < len; i++) {
        // dp の値をボトムアップに求めていく！→約数包除？
        vector<ll> vecs(i + 1, 0);
        for (ll j = i; j >= 0; j--) {
            vecs[j] = N / divs[j];
            for (ll k = j + 1; k <= i; k++) {
                if (divs[k] % divs[j] == 0 && divs[i] % divs[k] == 0) {
                    vecs[j] -= vecs[k];
                }
            }
        }
        double bunbo = 0;
        double bunshi = 0;
        ll vecs_all = 0;
        for (ll j = 0; j <= i; j++) {
            if (divs[i] % divs[j] == 0) {
                bunshi += (double)vecs[j];
                vecs_all += vecs[j];
                if (j < i) {
                    bunbo += (double)vecs[j];
                }
            }
        }
        // debug(vecs);
        // debug_out(i, bunshi, bunbo);
        for (ll j = 0; j < i; j++) {
            dp[i] += ((double)vecs[j] / bunbo) * dp[j];
        }
        dp[i] += (bunshi / bunbo);
    }
    // debug(dp);
    cout << setprecision(13) << dp[len - 1] << endl;
}