text: # ABC164a
  
  
  def main():
      import sys
      input = sys.stdin.readline
      sys.setrecursionlimit(10**6)
      # 再帰関数を使わない限りPypyで出すこと
  
      def dump(*args):
          sys.stderr.write(str(args))
  
      s, w = map(int, input().split())
      if s <= w:
          print('unsafe')
      else:
          print('safe')
  
  
  if __name__ == '__main__':
      main()
  