#include using namespace std; #define REP(i, n) for (int i=0; i<(n); ++i) #define RREP(i, n) for (int i=(int)(n)-1; i>=0; --i) #define FOR(i, a, n) for (int i=(a); i<(n); ++i) #define RFOR(i, a, n) for (int i=(int)(n)-1; i>=(a); --i) #define SZ(x) ((int)(x).size()) #define ALL(x) (x).begin(),(x).end() #define DUMP(x) cerr<<#x<<" = "<<(x)< ostream &operator<<(ostream &os, const vector &v) { os << "["; REP(i, SZ(v)) { if (i) os << ", "; os << v[i]; } return os << "]"; } template ostream &operator<<(ostream &os, const pair &p) { return os << "(" << p.first << " " << p.second << ")"; } template bool chmax(T &a, const T &b) { if (a < b) { a = b; return true; } return false; } template bool chmin(T &a, const T &b) { if (b < a) { a = b; return true; } return false; } using ll = long long; using ull = unsigned long long; using ld = long double; using P = pair; using vi = vector; using vll = vector; using vvi = vector; using vvll = vector; const ll MOD = 1e9 + 7; const int INF = INT_MAX / 2; const ll LINF = LLONG_MAX / 2; const ld eps = 1e-9; int main() { cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(10); double k; cin >> k; if(k == 0) { cout << 0 << endl; return 0; } double ans = 0; for(int i=1;i<=k;++i) { ans += 1.0 / i; } cout << ans / k << endl; return 0; }