(defun read-values (file)
  (with-open-file (stream file)
    (loop for value = (read stream NIL)
          while value collect value)))

(defun dip1 (file)
  (loop for (a b) on (read-values file)
        while b count (< a b)))

(defun dip2 (file)
  (loop with window = 0
        for (a b c) on (read-values file)
        while c
        count (< window (+ a b c))
        do (setf window (+ a b c))))