;; -*- coding: utf-8 -*-
(eval-when (:compile-toplevel :load-toplevel :execute)
  (sb-int:defconstant-eqx OPT
    #+swank '(optimize (speed 3) (safety 2))
    #-swank '(optimize (speed 3) (safety 0) (debug 0))
    #'equal)
  #+swank (ql:quickload '(:cl-debug-print :fiveam) :silent t)
  #-swank (set-dispatch-macro-character
           #\# #\> (lambda (s c p) (declare (ignore c p)) (read s nil nil t))))
#+swank (cl-syntax:use-syntax cl-debug-print:debug-print-syntax)
#-swank (disable-debugger) ; for CS Academy

;; BEGIN_INSERTED_CONTENTS
(defun binsort! (vector range-max &key from-end)
  (declare #.OPT
           ((simple-array (unsigned-byte 31) (*)) vector)
           ((mod #.array-total-size-limit) range-max))
  ;; If KEY is not given, all we need is counting sort.
  (let ((counts (make-array (1+ range-max) :element-type '(unsigned-byte 31) :initial-element 0)))
    (sb-int:dovector (e vector)
      (incf (aref counts e)))
    (let ((pos 0))
      (declare ((integer 0 #.most-positive-fixnum) pos))
      (if from-end
          (loop for x from range-max downto 0
                do (loop repeat (aref counts x)
                         do (setf (aref vector pos) x)
                            (incf pos)))
          (loop for x from 0 to range-max
                do (loop repeat (aref counts x)
                         do (setf (aref vector pos) x)
                            (incf pos))))))
  vector)

(declaim (ftype (function * (values fixnum &optional)) read-fixnum))
(defun read-fixnum (&optional (in *standard-input*))
  (declare #.OPT)
  (macrolet ((%read-byte ()
               `(the (unsigned-byte 8)
                     #+swank (char-code (read-char in nil #\Nul))
                     #-swank (sb-impl::ansi-stream-read-byte in nil #.(char-code #\Nul) nil))))
    (let* ((minus nil)
           (result (loop (let ((byte (%read-byte)))
                           (cond ((<= 48 byte 57)
                                  (return (- byte 48)))
                                 ((zerop byte) ; #\Nul
                                  (error "Read EOF or #\Nul."))
                                 ((= byte #.(char-code #\-))
                                  (setf minus t)))))))
      (declare ((integer 0 #.most-positive-fixnum) result))
      (loop
        (let* ((byte (%read-byte)))
          (if (<= 48 byte 57)
              (setq result (+ (- byte 48)
                              (* 10 (the (integer 0 #.(floor most-positive-fixnum 10)) result))))
              (return (if minus (- result) result))))))))

(defmacro dbg (&rest forms)
  #+swank
  (if (= (length forms) 1)
      `(format *error-output* "~A => ~A~%" ',(car forms) ,(car forms))
      `(format *error-output* "~A => ~A~%" ',forms `(,,@forms)))
  #-swank (declare (ignore forms)))

(defmacro define-int-types (&rest bits)
  `(progn
     ,@(mapcar (lambda (b) `(deftype ,(intern (format nil "UINT~A" b)) () '(unsigned-byte ,b))) bits)
     ,@(mapcar (lambda (b) `(deftype ,(intern (format nil "INT~A" b)) () '(signed-byte ,b))) bits)))
(define-int-types 2 4 7 8 15 16 31 32 62 63 64)

(declaim (inline println))
(defun println (obj &optional (stream *standard-output*))
  (let ((*read-default-float-format* 'double-float))
    (prog1 (princ obj stream) (terpri stream))))

(defconstant +mod+ 1000000007)

;;;
;;; Body
;;;


(defun main ()
  (declare #.OPT)
  (let* ((n (read))
         (k (read))
         (as (make-array n :element-type 'uint31))
         (fs (make-array n :element-type 'uint31)))
    (declare (uint62 n k))
    (dotimes (i n)
      (setf (aref as i) (read-fixnum)))
    (dotimes (i n)
      (setf (aref fs i) (read-fixnum)))
    (binsort! as 1000000)
    (binsort! fs 1000000 :from-end t)
    (let ((max (loop for a across as
                     for f across fs
                     maximize (* a f))))
      (labels ((feasible-p (obj)
                 (let ((count 0))
                   (declare (uint62 count))
                   (dotimes (i n t)
                     (let* ((a (aref as i))
                            (f (aref fs i))
                            (delta (max 0 (- (* a f) obj)))
                            (cost (ceiling delta f)))
                       (incf count cost)
                       (when (> count k)
                         (return nil)))))))
        (sb-int:named-let bisect ((ng -1) (ok max))
          (declare (fixnum ok ng))
          (if (<= (- ok ng) 1)
              (println ok)
              (let ((mid (floor (+ ok ng) 2)))
                (if (feasible-p mid)
                    (bisect ng mid)
                    (bisect mid ok)))))))))

#-swank (main)


Measured memory_bytes: 23016