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