#include <bits/stdc++.h>
using namespace std;
long long int mod1 = 998244353;
long long int mod = 1e9 + 7;
bool comp(pair<long long int, long long int> x,
          pair<long long int, long long int> y) {
  if (x.first < y.first) return true;
}
long long int a[200005];
void solve() {
  double ans = 0;
  long long int n;
  cin >> n;
  while (n) {
    ans += (double)1 / (double)n;
    n--;
  }
  cout << ans;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long int t = 1;
  while (t--) {
    solve();
    cout << "\n";
  }
  return 0;
}
