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())
  p = [0] * m
  V = [[] for i in range(n + 1)]
  for i in range(m):
      p[i] = list(map(int, input().split())) + [i]
      V[p[i][0]].append(p[i][1:])
  W = []
  for i in range(n + 1):
      if V[i] == []:
          pass
      else:
          V[i].sort(key=lambda val: val[0])
          for j in range(len(V[i])):
              K = (
                  ["0"] * (6 - len(str(i)))
                  + list(str(i))
                  + ["0"] * (6 - len(str(j + 1)))
                  + list(str(j + 1))
              )
              W.append(["".join(K), V[i][j][1]])
  W.sort(key=lambda val: val[1])
  for ans in W:
      print(ans[0])
  
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"}]