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())  # 5 7
  
  P = [0]
  Y = [0]
  A = []
  
  for i in range(M):
      p, y = map(int, input().split())  # 5 7
      P.append(p)
      Y.append(y)
      A.append([i, p, y, p * 1000000 + y])
  
  # print(N,M)
  # print(*P)
  # print(*Y)
  # print(*A)
  
  A = sorted(A, key=lambda x: x[3])
  
  # print(*A)
  
  p0 = 0
  no = 0
  for i in range(len(A)):
      a = A[i]
      p = a[1]
      y = a[2]
      # 	print(i,a,p,y)
  
      if p != p0:
          no = 0
      no += 1
      A[i].append(no)
  
      p0 = p
  
  # print(*A)
  
  A = sorted(A, key=lambda x: x[0])
  # print(*A)
  
  for a in A:
      p = "000000" + str(a[1])
      i = "000000" + str(a[4])
      print(p[-6:] + i[-6:])
  
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"}]