repeat
   print "Enter integral rainfall (99999 to quit): "
   i = number input
   until i = 99999
   if error = 1 or i < 0 or i mod 1 <> 0
      print "Must be an integer no less than 0, try again."
   else
      n += 1
      sum += i
      print "  The current average rainfall is " & sum / n
   .
.
