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: import sys
  
  
  # やけくそ
  def 解():
      iN, iM = [int(_) for _ in input().split()]
      aPM = [[int(_) for _ in sLine.split()] for sLine in sys.stdin.readlines()]
      dC = {}
  
      def addCity(d, p, m, i):
          if p in d:
              d[p].append((m, i))
          else:
              d[p] = [(m, i)]
  
      iIndex = 1
      for p, m in aPM:
          addCity(dC, p, m, iIndex)
          iIndex += 1
      oAns = []
  
      for iCity in dC.keys():
          iIndex = 1
          for m, i in sorted(list(dC[iCity])):
              oAns.append((i, "{:06}{:06}".format(iCity, iIndex)))
              iIndex += 1
      oAns.sort()
      oAns2 = []
      for i, s in oAns:
          oAns2.append(s)
      print("\n".join(oAns2))
  
  
  解()
  
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"}]