#include<stdio.h>

int main()

{

int n,k;

double s, i,j;

scanf_s("%d", &k);

s = 0;

i = 1.0;

n = 1;

while (n>k)

{

j=i/ n;

s += j;

i = -i;

n++;

}

printf("s=%f", s);

while (1);