#include <stdio.h>

int main()

{
float  n, i, l;
l=1;

do {
printf ("Parakalo doste enan arithmo megalytero tou 3:\n");
scanf ("%f", &n);
}while (n<4);

for(i=2;i<(n+1);i=i+1){
l=l+1/n;
}

printf("%f \n", l);
return 0;
}