*Factor* prints
*number* and its prime factors,
each repeated the proper number of times.
The number must be positive and less than
2^{54}
(about
1.8×10^{16}).
If no
*number* is given,
*factor* reads a stream of numbers from the standard input and factors them.
It exits on any input not a positive integer.
Maximum running time is proportional to
*v/n*^{–}.

*Primes* prints the prime numbers ranging from
*start* to
*finish*, where
*start* and
*finish* are positive numbers less than
2^{56}.
If
*finish* is missing,
*primes* prints without end;
if
*start* is missing, it reads the starting number from the
standard input.