output_description: Print the ID numbers for all the cities, in ascending order of indices (City
  1, City 2, ...).
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N M
      P_1 Y_1
      :
      P_M Y_M
attempt: N, M = map(int, input().split())  # N個の県, M個の市
  
  city_info = []
  for i in range(M):  # M個の市の情報
      p, y = map(int, input().split())  # どこの県に属するかの情報p, 誕生した年y
      city_info.append(
          [i + 1, p, y, -1]
      )  # 市のインデックス, 属する県, 誕生した年, 何番目に誕生した
  
  city_info = sorted(city_info, key=lambda x: (x[1], x[2]))  # 属する県でソート
  
  # print(city_info)
  
  now_pref = city_info[0][1]
  
  tmp = 0
  for i in range(M):
      if city_info[i][1] == now_pref:
          tmp += 1
          city_info[i][3] = tmp
      else:
          tmp = 1
          city_info[i][3] = tmp
          now_pref = city_info[i][1]
  
  city_info = sorted(city_info, key=lambda x: x[0])
  
  # print(city_info)
  
  
  for i in range(M):
      str_p = str(city_info[i][1])
      str_zyunban = str(city_info[i][3])
  
      lack_p = 6 - len(str_p)
      str_p = "0" * lack_p + str_p
  
      lack_zyunban = 6 - len(str_zyunban)
      str_zyunban = "0" * lack_zyunban + str_zyunban
  
      print(str_p + str_zyunban)
  
problem_description: 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.
samples: [{"input": "2 3\n    1 32\n    2 63\n    1 12", "output": "000001000002\n    000002000001\n    000001000001\n    \n\n  * As City 1 is the second established city among the cities that belong to Prefecture 1, its ID number is 000001000002.\n  * As City 2 is the first established city among the cities that belong to Prefecture 2, its ID number is 000002000001.\n  * As City 3 is the first established city among the cities that belong to Prefecture 1, its ID number is 000001000001.\n\n* * *"}, {"input": "2 3\n    2 55\n    2 77\n    2 99", "output": "000002000001\n    000002000002\n    000002000003"}]