Ackerman: procedure (m, n) returns (fixed (30)) recursive;
   declare (m, n) fixed (30);
   if m = 0 then return (n+1);
   else if m > 0 & n = 0 then return (Ackerman(m-1, 1));
   else if m > 0 & n > 0 then return (Ackerman(m-1, Ackerman(m, n-1)));
   return (0);
end Ackerman;