(defparameter +dx+ (make-array 4 :element-type 'integer :initial-contents '(1 0 -1 0)))
(defparameter +dy+ (make-array 4 :element-type 'integer :initial-contents '(0 -1 0 1)))
(defvar *que* (make-array 1010101))
(defvar *que-front* 0)
(defvar *que-back* 0)

(defun main (&rest argv)
  (declare (ignorable argv))
  (let* ((n (read))
         (taro-hp (read))
         (start-x (1- (read)))
         (start-y (1- (read)))
         (goal-x (1- (read)))
         (goal-y (1- (read)))
         (desert-levels (make-array (list n n) :element-type 'integer))
         (dp1 (make-array (list n n) :element-type 'integer :initial-element 0))
         (dp2 (make-array (list n n) :element-type 'integer :initial-element 0)))
    (dotimes (i n) (dotimes (j n) (setf (aref desert-levels i j) (read))))
    (setf (aref dp1 start-y start-x) taro-hp)
    (setf (aref *que* *que-front*) (cons start-x start-y))
    (incf *que-front*)
    (loop while (> *que-front* *que-back*) do
          (let* ((now (aref *que* *que-back*))
                 (x (car now))
                 (y (cdr now)))
            (incf *que-back*)
            (dotimes (k 4)
              (let ((xx (+ x (aref +dx+ k)))
                    (yy (+ y (aref +dy+ k))))
                (unless (or (or (< xx 0) (<= n xx) (< yy 0) (<= n yy))
                            (>= (aref dp1 yy xx) (- (aref dp1 y x) (aref desert-levels yy xx))))
                        (setf (aref dp1 yy xx) (- (aref dp1 y x) (aref desert-levels yy xx))
                              (aref dp2 yy xx) (1+ (aref dp2 y x))
                              (aref *que* *que-front*) (cons xx yy))
                        (incf *que-front*)
                        (when (and (= xx goal-x) (= yy goal-y))
                              (format t "~d~%" (aref dp2 yy xx))
                              (return-from main 0)))))))
    (format t "-1~%"))
  0)

(main)