PRIME1 - first attempt

Not fast enough.
PRIME1 -- second attempt

- Sieve up to sqrt(end)

- Segmented sieve

Not fast enough.
PRIME1 - solution

- Don't sieve even numbers.  Even numbers cause a lot of unnecessary
  calculations and memory usage.  So instead of sieving them, just check for
  evenness when outputting and only sieve odd numbers.

This barely got it under the time limit.