let
 function fib(n) =
  if n = 0 then 0
  else if n = 1 then 1
  else fib(n - 2) + fib(n - 1)
 var i := 0
in
 while i <= 42 do
  (print(showint(fib(i)));
   newline();
   i := i + 1)
end