#include // #include using namespace std; // using namespace atcoder; #define rep2(i,m,n) for (int i = (m); i < (n); ++i) #define rep(i,n) rep2(i,0,n) #define debug(x) cout << x << endl; typedef long long int ll; typedef long double ld; typedef pair P; template struct V : vector { using vector::vector; }; V() -> V; V(size_t) -> V; template V(size_t, T) -> V; template vector make_vec(size_t n, T a) { return vector(n, a); } template auto make_vec(size_t n, Ts... ts) { return vector(n, make_vec(ts...)); } template ostream &operator<<(ostream &os, const vector &v) { for (auto &e : v) os << e << ' '; return os; } struct fast_ios { fast_ios(){ cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_; template inline bool chmin(T &a, T b) { if (a > b) { a = b; return true; } return false; } template inline bool chmax(T &a, T b) { if (a < b) { a = b; return true; } return false; } const int INF = 1<<30; const ll LINF = 1LL<<61; // const ll MOD = 1000000007; // using mint = modint1000000007; ld eps = 1e-12; ld power(ld x, int k) { ld res = 1; while(k) { if(k & 1) res = (res * x); k >>= 1; x = (x * x); } return res; } ld sum(ll n, ld r) { return (ld)r / (ld)(1 - r) - (r - power(r, n+1)) / (1 - r); } int main() { ll n; cin >> n; if(n == 2) { cout << 999999 << endl; return 0; } ld ans = 0; for(ll i=2; i<101010; i++) { ld tmp = sum(n-1, (ld)1 / (ld)i); ans += tmp; } ll res = (ans * 1e9) + eps; res /= 1000; cout << res << endl; return 0; }