Problem:
Score: 300 points

Problem Statement

In Republic of Atcoder, there are N prefectures, and a total of M cities that belong to those prefectures.

City i is established in year Y_i and belongs to Prefecture P_i.

You can assume that there are no multiple cities that are established in the same year.

It is decided to allocate a 12-digit ID number to each city.

If City i is the x-th established city among the cities that belong to Prefecture i, the first six digits of the ID number of City i is P_i, and the last six digits of the ID number is x.

Here, if P_i or x (or both) has less than six digits, zeros are added to the left until it has six digits.

Find the ID numbers for all the cities.

Note that there can be a prefecture with no cities.

Constraints

1 \leq N \leq 10^5

1 \leq M \leq 10^5

1 \leq P_i \leq N

1 \leq Y_i \leq 10^9

Y_i are all different.

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N M
P_1 Y_1
:
P_M Y_M

Output

Print the ID numbers for all the cities, in ascending order of indices (City 1, City 2, ...).

Sample Input 1

2 3
1 32
2 63
1 12

Sample Output 1

000001000002
000002000001
000001000001

As City 1 is the second established city among the cities that belong to Prefecture 1, its ID number is 000001000002.

As City 2 is the first established city among the cities that belong to Prefecture 2, its ID number is 000002000001.

As City 3 is the first established city among the cities that belong to Prefecture 1, its ID number is 000001000001.

Sample Input 2

2 3
2 55
2 77
2 99

Sample Output 2

000002000001
000002000002
000002000003

Solution in Common Lisp (SBCL 1.1.14) (judge verdict: Accepted)

(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 split-and-bind (arg-lst string &body body)
  (let ((pos1 (gensym "POS"))
	(pos2 (gensym "POS"))
	(str (gensym "STR")))
    (labels ((expand (arg-lst &optional (init-pos1 t))
	       (if (null arg-lst)
		   body
		   `((let* ((,pos1 ,(if init-pos1 0 `(1+ ,pos2)))
			    (,pos2 (position #\space ,str :start ,pos1 :test #'char=))
			    (,(car arg-lst) (parse-integer ,str :start ,pos1 :end ,pos2)))
		       ,@(expand (cdr arg-lst) nil))))))
      `(let ((,str ,string))
         (declare (string ,str))
	 ,@(expand arg-lst)))))

(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 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))))

;; Hauptteil

(defstruct city
  (year 0 :type uint31)
  (prefecture 0 :type uint31)
  (version 0 :type uint31))

(defun main ()
  (let* ((n (read))
         (m (read))
         (p-table (make-array (list (1+ n)) :element-type 'list :initial-element nil))
         (city-table (make-array (list m) :element-type 'list :initial-element nil)))
    ;; node := (prefecture year version)
    (dotimes (city-idx m)
      (split-and-bind (prefecture year) (read-line)
        (let ((node (make-city :prefecture prefecture :year year)))
          (push node (aref p-table prefecture))
          (setf (aref city-table city-idx) node))))
    (loop for p-idx from 1 to n
          do (setf (aref p-table p-idx)
                   (sort (aref p-table p-idx) #'< :key #'city-year))
             (loop for node in (aref p-table p-idx)
                   for version from 1
                   do (setf (city-version node) version)))
    (dotimes (city-idx m)
      (format t "~6,'0D~6,'0D~%"
              (city-prefecture (aref city-table city-idx))
              (city-version (aref city-table city-idx))))))

#-swank(main)