#include <bits/stdc++.h>
using namespace std;
bool func(const pair<long long, long long> &a,
          const pair<long long, long long> &b) {
  return a.second < b.second;
}
long long int power(long long int x, long long int y) {
  if (y == 0)
    return 1;
  else if (y % 2 == 0)
    return ((power(x, y / 2) % 1000000007) * (power(x, y / 2) % 1000000007) %
            1000000007);
  else
    return (x * ((power(x, y / 2) % 1000000007) *
                 (power(x, y / 2) % 1000000007) % 1000000007)) %
           1000000007;
}
long long int modInverse(long long int a, long long int m) {
  long long int m0 = m;
  long long int y = 0, x = 1;
  if (m == 1) return 0;
  while (a > 1) {
    long long int q = a / m;
    long long int t = m;
    m = a % m, a = t;
    t = y;
    y = x - q * y;
    x = t;
  }
  if (x < 0) x += m0;
  return x;
}
void solve(int t) {
  long long int n;
  cin >> n;
  double res = 0;
  while (n) {
    res += (1.0 / n);
    n--;
  }
  cout << setprecision(20) << res;
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int t, tmp = 0;
  t = 1;
  while (tmp++ < t) {
    solve(tmp - 1);
    if (t - tmp) cout << "\n";
  }
  return 0;
}
