#include<stdio.h> 
int main()
{
    double n,i,s=0;
    scanf("%lf",&n); 
    for(i=1; i<=n ;i++)
    {
             s= s+1/i;
    }
    printf("%.3lf\n",s);
    return 0;
}
/**************************************************************
	Problem: 1014
	User: admin
	Language: C
	Result: Accepted
	Time:9 ms
	Memory:1144 kb
****************************************************************/