/*
7-7 ?e????
?? 10
?? C???
?? ????
???? e ????? 1+1/1!+1/2!+?+1/n!+? ?????????????????? n,?????? n+1 ???

????:
???????????? n(=1000)?

????:
???????????,?????????

????:
10
????:
2.71828180
*/

#include<stdio.h>
int main(){
	int n;
	scanf("%d",&n);
	double sum=1.0,tag=1.0;
	for(int i=1;i<=n;i++){
		tag=tag*1.0/i;
		sum+=tag;
	}
	printf("%.8lf",sum);
	return 0;
}