test: proc options (main);
   declare (longest, n) fixed (15);
   declare flag bit (1);
   declare (i, value) fixed (15);

   /* Task 1: */
   flag = '1'b;
   put skip list ('The sequence for 27 is');
   i = hailstones(27);

   /* Task 2: */
   flag = '0'b;
   longest = 0;
   do i = 1 to 99999;
      if longest < hailstones(i) then
         do; longest = hailstones(i); value = i; end;
   end;
   put skip edit (value, ' has the longest sequence of ', longest) (a);

hailstones: procedure (n) returns ( fixed (15));
   declare n fixed (15) nonassignable;
   declare (m, p) fixed (15);

   m = n;
   p = 1;
   if flag then put skip list (m);
   do p = 1 by 1 while (m > 1);
      if iand(m, 1) = 0 then
         m = m/2;
      else
         m = 3*m + 1;
      if flag then put skip list (m);
   end;
   if flag then put skip list ('The hailstone sequence has length' || p);
   return (p);
end hailstones;

end test;