fastfunc isprim num .
   i = 2
   while i <= sqrt num
      if num mod i = 0
         return 0
      .
      i += 1
   .
   return 1
.
for i = 7 step 2 to 999
   if isprim i = 1 and isprim (i - 4) = 1
      write "(" & i - 4 & " " & i & ") "
   .
.
