(let ((x (read))
      (y (read))
      (str (read-line)))
  (multiple-value-bind (a b) (parse-integer str :junk-allowed t)
    (multiple-value-bind (c d) (parse-integer str :start (1+ b) :junk-allowed t)
      (if (and (= x b) (= y (- d 1 b)) a c)
          (princ "Yes")
          (princ "No")))))