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
  
  input = sys.stdin.readline
  
  
  def binary_search(list, item):
      low = 0
      high = len(list) - 1
  
      while low <= high:
          mid = (low + high) // 2
          guess = list[mid]
          if guess == item:
              return mid
          if guess > item:
              high = mid - 1
          else:
              low = mid + 1
  
  
  n, m = map(int, input().split())
  py = [list(map(int, input().split())) for i in range(m)]
  check = sorted(py)
  memo = py[0][0]
  cnt = [0] * m
  cnt_memo = 0
  
  for i in range(m):
      if memo != check[i][0]:
          memo = check[i][0]
          cnt_memo = 0
      cnt_memo += 1
      cnt[i] = cnt_memo
  
  for i in range(m):
      number = str(cnt[binary_search(check, py[i])])
      p = str(py[i][0])
      print((6 - len(p)) * "0" + p + (6 - len(number)) * "0" + number)
  
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"}]