#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  scanf("%d", &n);
  double dp[100005];
  for (int i = 0; i <= n; i++) dp[i] = 0.0;
  dp[1] = 1.0;
  for (int i = 2; i <= n; i++) {
    double add = 1.0;
    add /= i;
    dp[i] = dp[i - 1] + add;
  }
  cout << dp[n] << endl;
}
