(eval-when (:compile-toplevel :load-toplevel :execute)
  (defparameter OPT
    #+swank '(optimize (speed 3) (safety 2))
    #-swank '(optimize (speed 3) (safety 0) (debug 0)))
  #+swank (progn (ql:quickload '(:cl-debug-print :fiveam))
                 (shadow :run)
                 (use-package :fiveam)))
#+swank (cl-syntax:use-syntax cl-debug-print:debug-print-syntax)

;; BEGIN_INSERTED_CONTENTS
(defmacro buffered-read-line (&optional (buffer-size 30) (in '*standard-input*) (terminate-char #\Space))
  "Note that the returned string will be reused."
  (let ((buffer (gensym))
        (character (gensym))
        (idx (gensym)))
    `(let ((,buffer (load-time-value (make-string ,buffer-size
                                                  :element-type 'base-char))))
       (declare (simple-base-string ,buffer))
       (loop for ,character of-type base-char =
                #-swank (code-char (read-byte ,in nil #.(char-code #\Newline)))
                #+swank (read-char ,in nil #\Newline)
             for ,idx from 0
             until (char= ,character #\Newline)
             do (setf (schar ,buffer ,idx) ,character)
             finally (when (< ,idx ,buffer-size)
                       (setf (schar ,buffer ,idx) ,terminate-char))
                     (return (values ,buffer ,idx))))))

(defmacro split-ints-bind (vars string &body body)
  (let ((position (gensym))
        (s (gensym)))
    (labels ((expand (vars &optional init-pos)
               (if (null vars)
                   body
                   `((multiple-value-bind (,(car vars) ,position)
                         (parse-integer ,s :start ,(or init-pos position)
                                           :junk-allowed t)
                       ,@(when (null (cdr vars)) `((declare (ignore ,position))))
                       ,@(expand (cdr vars)))))))
      `(let ((,s ,string))
         (declare (string ,s))
         ,@(expand vars 0)))))

(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)

(defmacro println (obj &optional (stream '*standard-output*))
  `(let ((*read-default-float-format* 'double-float))
     (prog1 (princ ,obj ,stream) (terpri ,stream))))

(defconstant +mod+ 1000000007)

;; Hauptteil

(defun main ()
  (declare #.OPT (inline sort))
  (let* ((n (read))
         (m (read))
         ;; (cost . max)
         (table (make-array n :element-type '(cons uint31 uint31))))
    (declare ((integer 1 100000) n m))
    (dotimes (i n)
      (split-ints-bind (a b) (buffered-read-line 17)
        (setf (aref table i) (cons a b))))
    (setf table (sort table
                      (lambda (x y) (declare (uint31 x y)) (< x y))
                      :key #'car))
    (let ((cost-sum 0)
          (cumul 0))
      (declare (uint62 cost-sum)
               ((integer 0 100000) cumul))
      (loop for i below n
            for (cost . limit) of-type (uint31 . uint31) = (aref table i)
            do (if (>= (+ cumul limit) m)
                   (progn (incf cost-sum (* cost (- m cumul)))
                          (loop-finish))
                   (progn (incf cumul limit)
                          (incf cost-sum (* cost limit)))))
      (println cost-sum))))

#-swank(main)


Measured memory_bytes: 30564