#include <stdio.h>
double prob(int n)
{
    double k, b;
    unsigned int i;
    k = -1;
    b = 1;
    for (i = 2; i <= n; i++)
    {
        k = k + b / i;
        b = -b;
    }
    return(k);
}
int main(void)
{
    int h;
    double l;
    scanf("%d", &h);
    l = prob(h);
    printf("%lf", l);
    return 0;
}