#include <bits/stdc++.h>
using namespace std;
int main(){
    int n,i=1;
    float a=0;
    cin>>n;
    while(i<=n){
        a=a+1.0/i;
        i++;    
    }
    printf("%.3f",a);
}
/**************************************************************
	Problem: 1014
	User: linzihang
	Language: C++
	Result: Accepted
	Time:10 ms
	Memory:2072 kb
****************************************************************/