/**
 *   @FileName	a.cpp
 *   @Author	kanpurin
 *   @Created	2020.10.30 21:32:00
**/

#include "bits/stdc++.h" 
using namespace std; 
typedef long long ll;

int main() {
    ll k;cin >> k;
    if (k >= 10000000) {
        printf("%.10f\n",log(k)/k);
    }
    else {
        double ans = 0;
        for (int i = 1; i <= k; i++) {
            ans += 1.0/i;
        }
        printf("%.10f\n",ans/k);
    }
    return 0;
}