#include<stdio.h>
int main(){
 	int n,i,j;
	double sum;
	sum=0;
	j=1;
	scanf("%d",&n);
	while(n>=1){
		for(i=1;i<=n;i++){
		j*=i;
		if(i==n){
			sum=sum+1.0/(double)j;
			n--;
			j=1;
		}
	} 
	}
	printf("%.10lf",sum);
	return 0;
}