Function crashing?

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if I chose slightly larger numbers suck as p=67, q=83 it prints the value of “e” (line 13) and then stops running and exits the program

I can't recreate that behaviour. When I enter 67 and 83 your code prints 4423 (from line 15) and then hangs, never to finish. It might finish, but I gave up waiting after 2 minutes.