#include <bits/stdc++.h>
using namespace std;
int main(){
    int n,i=1;
    float h=0; 
    cin>>n;
    for(i=1;i<=n;i++){
        h=h+1.0/i;
    }
    printf("%.3f",h);
}
/**************************************************************
	Problem: 1014
	User: hongguangxi
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/