output_description: If he can achieve the objective, print `OK`; if he cannot, print `NG`.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      K
      A B
attempt: N, M = list(map(int, input().split()))
  src = [i + 1 for i in range(M * 2 + 1)]
  if N % 2 == 0:
      for m in range(M // 2):
          a = src[m]
          b = src[M - m]
          print("{} {}".format(a, b))
      for m in range(M // 2):
          a = src[M + 1 + m]
          b = src[-(m + 1)]
          print("{} {}".format(a, b))
  else:
      for m in range(M // 2):
          a = src[m]
          b = src[M - 1 - m]
          print("{} {}".format(a, b))
      for m in range(M - (M // 2)):
          a = src[M + m]
          b = src[-(m + 1)]
          print("{} {}".format(a, b))
  
problem_description: Statement
  
  Takahashi the Jumbo will practice golf.
  
  His objective is to get a carry distance that is a multiple of K, while he can
  only make a carry distance of between A and B (inclusive).
  
  If he can achieve the objective, print `OK`; if he cannot, print `NG`.
samples: [{"input": "7\n    500 600", "output": "OK\n    \n\nAmong the multiples of 7, for example, 567 lies between 500 and 600.\n\n* * *"}, {"input": "4\n    5 7", "output": "NG\n    \n\nNo multiple of 4 lies between 5 and 7.\n\n* * *"}, {"input": "1\n    11 11", "output": "OK"}]