output_description: Print M lines in the format below. The i-th line should contain the two
  integers a_i and b_i assigned to the i-th playing field.
  
      
      
      a_1 b_1
      a_2 b_2
      :
      a_M b_M
      
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N M
attempt: # coding: utf-8
  import sys
  
  sr = lambda: sys.stdin.readline().rstrip()
  ir = lambda: int(sr())
  lr = lambda: list(map(int, sr().split()))
  
  # M個用意する対戦場の数字の差が異なるようにする
  N, M = lr()
  answer = [[0, 0] for _ in range(M)]
  if N & 1:
      for i in range(M):
          answer[i][0] = i + 1
  
      cur = M + 1
      used = set()
      for i in range(M - 1, -1, -1):
          while cur - answer[i][0] in used:
              cur += 1
          answer[i][1] = cur
          diff = answer[i][1] - answer[i][0]
          used.add(diff)
          cur += 1
  else:
      l = list(range(1, M + 1))
      odd = [x for x in l if x & 1]
      even = [x for x in l if x % 2 == 0]
      cur = 0
      for x in odd[::-1]:
          answer[cur] = [cur + 1, cur + 1 + x]
          cur += 1
      now = 1 + odd[-1] + 1
      for x in even[::-1]:
          answer[cur] = [now, now + x]
          now += 1
          cur += 1
  
  for a in answer:
      if a[0] == 0:
          continue
      print(*a)
  
problem_description: Statement
  
  You are going to hold a competition of one-to-one game called AtCoder Janken.
  _(Janken is the Japanese name for Rock-paper-scissors.)_ N players will
  participate in this competition, and they are given distinct integers from 1
  through N. The arena has M playing fields for two players. You need to assign
  each playing field two distinct integers between 1 and N (inclusive). You
  cannot assign the same integer to multiple playing fields. The competition
  consists of N rounds, each of which proceeds as follows:
  
    * For each player, if there is a playing field that is assigned the player's integer, the player goes to that field and fight the other player who comes there.
    * Then, each player adds 1 to its integer. If it becomes N+1, change it to 1.
  
  You want to ensure that no player fights the same opponent more than once
  during the N rounds. Print an assignment of integers to the playing fields
  satisfying this condition. It can be proved that such an assignment always
  exists under the constraints given.
samples: [{"input": "4 1", "output": "2 3\n    \n\nLet us call the four players A, B, C, and D, and assume that they are\ninitially given the integers 1, 2, 3, and 4, respectively.\n\n  * The 1-st round is fought by B and C, who has the integers 2 and 3, respectively. After this round, A, B, C, and D have the integers 2, 3, 4, and 1, respectively.\n\n  * The 2-nd round is fought by A and B, who has the integers 2 and 3, respectively. After this round, A, B, C, and D have the integers 3, 4, 1, and 2, respectively.\n\n  * The 3-rd round is fought by D and A, who has the integers 2 and 3, respectively. After this round, A, B, C, and D have the integers 4, 1, 2, and 3, respectively.\n\n  * The 4-th round is fought by C and D, who has the integers 2 and 3, respectively. After this round, A, B, C, and D have the integers 1, 2, 3, and 4, respectively.\n\nNo player fights the same opponent more than once during the four rounds, so\nthis solution will be accepted.\n\n* * *"}, {"input": "7 3", "output": "1 6\n    2 5\n    3 4"}]