#include <bits/stdc++.h>

using i64 = long long;
using i64 = long long;

template<class T>
constexpr T power(T a, i64 b) {
    T res = 1;
    for (; b; b /= 2, a *= a) {
        if (b % 2) {
            res *= a;
        }
    }
    return res;
}

constexpr i64 mul(i64 a, i64 b, i64 p) {
    i64 res = a * b - i64(1.L * a * b / p) * p;
    res %= p;
    if (res < 0) {
        res += p;
    }
    return res;
}

template<i64 P>
struct MLong {
    i64 x;

    constexpr MLong() : x{} {}

    constexpr MLong(i64 x) : x{norm(x % getMod())} {}

    static i64 Mod;

    constexpr static i64 getMod() {
        if (P > 0) {
            return P;
        } else {
            return Mod;
        }
    }

    constexpr static void setMod(i64 Mod_) {
        Mod = Mod_;
    }

    constexpr i64 norm(i64 x) const {
        if (x < 0) {
            x += getMod();
        }
        if (x >= getMod()) {
            x -= getMod();
        }
        return x;
    }

    constexpr i64 val() const {
        return x;
    }

    explicit constexpr operator i64() const {
        return x;
    }

    constexpr MLong operator-() const {
        MLong res;
        res.x = norm(getMod() - x);
        return res;
    }

    constexpr MLong inv() const {
        assert(x != 0);
        return power(*this, getMod() - 2);
    }

    constexpr MLong &operator*=(MLong rhs) &{
        x = mul(x, rhs.x, getMod());
        return *this;
    }

    constexpr MLong &operator+=(MLong rhs) &{
        x = norm(x + rhs.x);
        return *this;
    }

    constexpr MLong &operator-=(MLong rhs) &{
        x = norm(x - rhs.x);
        return *this;
    }

    constexpr MLong &operator/=(MLong rhs) &{
        return *this *= rhs.inv();
    }

    friend constexpr MLong operator*(MLong lhs, MLong rhs) {
        MLong res = lhs;
        res *= rhs;
        return res;
    }

    friend constexpr MLong operator+(MLong lhs, MLong rhs) {
        MLong res = lhs;
        res += rhs;
        return res;
    }

    friend constexpr MLong operator-(MLong lhs, MLong rhs) {
        MLong res = lhs;
        res -= rhs;
        return res;
    }

    friend constexpr MLong operator/(MLong lhs, MLong rhs) {
        MLong res = lhs;
        res /= rhs;
        return res;
    }

    friend constexpr std::istream &operator>>(std::istream &is, MLong &a) {
        i64 v;
        is >> v;
        a = MLong(v);
        return is;
    }

    friend constexpr std::ostream &operator<<(std::ostream &os, const MLong &a) {
        return os << a.val();
    }

    friend constexpr bool operator==(MLong lhs, MLong rhs) {
        return lhs.val() == rhs.val();
    }

    friend constexpr bool operator!=(MLong lhs, MLong rhs) {
        return lhs.val() != rhs.val();
    }
};

template<>
i64 MLong<0LL>::Mod = i64(1E18) + 9;

template<int P>
struct MInt {
    int x;

    constexpr MInt() : x{} {}

    constexpr MInt(i64 x) : x{norm(x % getMod())} {}

    static int Mod;

    constexpr static int getMod() {
        if (P > 0) {
            return P;
        } else {
            return Mod;
        }
    }

    constexpr static void setMod(int Mod_) {
        Mod = Mod_;
    }

    constexpr int norm(int x) const {
        if (x < 0) {
            x += getMod();
        }
        if (x >= getMod()) {
            x -= getMod();
        }
        return x;
    }

    constexpr int val() const {
        return x;
    }

    explicit constexpr operator int() const {
        return x;
    }

    constexpr MInt operator-() const {
        MInt res;
        res.x = norm(getMod() - x);
        return res;
    }

    constexpr MInt inv() const {
        assert(x != 0);
        return power(*this, getMod() - 2);
    }

    constexpr MInt &operator*=(MInt rhs) &{
        x = 1LL * x * rhs.x % getMod();
        return *this;
    }

    constexpr MInt &operator+=(MInt rhs) &{
        x = norm(x + rhs.x);
        return *this;
    }

    constexpr MInt &operator-=(MInt rhs) &{
        x = norm(x - rhs.x);
        return *this;
    }

    constexpr MInt &operator/=(MInt rhs) &{
        return *this *= rhs.inv();
    }

    friend constexpr MInt operator*(MInt lhs, MInt rhs) {
        MInt res = lhs;
        res *= rhs;
        return res;
    }

    friend constexpr MInt operator+(MInt lhs, MInt rhs) {
        MInt res = lhs;
        res += rhs;
        return res;
    }

    friend constexpr MInt operator-(MInt lhs, MInt rhs) {
        MInt res = lhs;
        res -= rhs;
        return res;
    }

    friend constexpr MInt operator/(MInt lhs, MInt rhs) {
        MInt res = lhs;
        res /= rhs;
        return res;
    }

    friend constexpr std::istream &operator>>(std::istream &is, MInt &a) {
        i64 v;
        is >> v;
        a = MInt(v);
        return is;
    }

    friend constexpr std::ostream &operator<<(std::ostream &os, const MInt &a) {
        return os << a.val();
    }

    friend constexpr bool operator==(MInt lhs, MInt rhs) {
        return lhs.val() == rhs.val();
    }

    friend constexpr bool operator!=(MInt lhs, MInt rhs) {
        return lhs.val() != rhs.val();
    }
};

template<>
int MInt<0>::Mod = 998244353;

template<int V, int P>
constexpr MInt<P> CInv = MInt<P>(V).inv();

constexpr int P = 1000000007;
using Z = MInt<P>;

using l64 = long double;

void solve() {
    int k;
    std::cin >> k;
    //f[i] = p*(f[i+1]+1)+p*(f[i+2]+1)... ==> f[i] = 1 + sum/p f0/p*x
    std::vector<l64> f(k + 1), K(k + 1), b(k + 1);
    l64 p = 1.0 / 6;
    for (int i = k - 1; i >= 0; i--) {
        for (int j = i + 1, s = 1; s <= 6; s++, j++) {
            if (j <= k) {
                K[i] += p * K[j];
                b[i] += p * b[j];
            } else {
                K[i] += p;
            }
        }
        b[i] += 1;
    }
    //f0 = k0*f0+b0
    l64 ans = b[0] / (1 - K[0]);
    std::cout << std::fixed << std::setprecision(10) << ans << "\n";
}

signed main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    int T = 1;
    //std::cin >> T;
    while (T--) solve();
    return 0;
}