#include <stdio.h>

int main()
{
	int n = 0; 
	double sum = 0.0; 
	scanf("%d", &n); 
	for (int i = 2; i <= n; i++)
	{
		sum += 1.0 / i; 
	}
	printf("%lf\n", 1 + sum); 
	return 0; 
}