#include <bits/stdc++.h>
using namespace std;
int n, k[100005];
double D[100005];
int main() {
  scanf("%d", &n);
  D[1] = 1;
  for (int i = 2; i <= n; i++) {
    D[i] = D[i - 1] + 1.0 / i;
  }
  printf("%f", D[n]);
  return 0;
}
