#job 23

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int factorial(int n)
{
	int i,tot = 1;
	for(i = 1 ; i <= n;i++)
		tot *= i;
	return tot;
}
int main()
{
	int n,i;
	double sum; 
	while(scanf("%d",&n)&&n)
	{
		if(n < 0)
			printf("Error!\n");
		else
		{
			sum = 0;
			for(i = 1 ; i <= n ;i++)
				sum += (double)(1.0/factorial(i));
			printf("s = %.8lf\n",sum);
		}
	}
	return 0;
}