#include <stdio.h>

/* S = 1/(1+1/(2+1/(....+1/(n-1+1/n)))))))) */

int main(){
	unsigned n;
	scanf("%u",&n);
	double sum = 1;
	while(n>1){
		sum=(n-1)+sum;
		sum = 1/sum;
		n--;
	}
	printf("%4.lf\n",sum);
	return 0;
}