C :

#include <stdio.h>
double total(int n);
int main()
{
	int n;
	scanf("%d",&n);
	printf("%.3lf\n",total(n));
	return 0;
}
double total(int n)
{
	double i,sum;
	for (i=1;i<=n;i++)
	{
		sum+=1/i;
	}
	return sum;
}

C++ :

#include<iostream>
#include<cstdio>
using namespace std;
double total(int n)
{
	double s=0;
	for (int i=1; i<=n; i++) s+=1.0/i;
	return s;
}
int main()
{
	int n;
	cin>>n;
	printf("%.3lf\n",total(n));
	return 0;
}