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 = [int(i) for i in input().split()]
  data = list()
  data_dict = dict()
  ind = 1
  for i in range(M):
      p, y = [int(i) for i in input().split()]
      data.append([i, p, y])
  data.sort(key=lambda x: (x[1], x[2]))
  ranked_data = list()
  for j, (i, p, y) in enumerate(data):
      if data[j - 1][1] != p and j > 1:
          ind = 1
      ranked_data.append([i, p, y] + [ind])
      ind += 1
  
  
  def num2str(num, len_str=6):
      return "0" * (len_str - len(str(num))) + str(num)
  
  
  ranked_data.sort(key=lambda x: x[0])
  for i, p, y, rank in ranked_data:
      print(num2str(p) + num2str(rank))
  
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"}]