output_description: Print the cost of the Ferris wheel for Takahashi.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      A B
attempt: # -*- coding: utf-8 -*-
  l = [0]
  r = [0]
  all_gate_clear = 0
  
  
  # numcard
  # gatenum
  N, M = map(int, input().split())
  card_count = range(N + 1)
  
  # idカードの生成
  for i in range(1, M + 1):
      l_temp, r_temp = map(int, input().split())
      l.append(l_temp)
      r.append(r_temp)
  
  for gate_num in range(1, M + 1):
      # 1ゲートの処理
      for card in range(1, N + 1):
          num = 0
          while r[gate_num] > l[gate_num] + num:
              if l[gate_num] + num == card:
                  if card_count[card] == gate_num - 1:
                      card_count[card] += 1
                      break
              num += 1
  
  for card in range(1, N + 1):
      if card_count[card] == M:
          all_gate_clear += 1
  
  print(all_gate_clear)
  
problem_description: Statement
  
  Takahashi, who is A years old, is riding a Ferris wheel.
  
  It costs B yen (B is an even number) to ride the Ferris wheel if you are 13
  years old or older, but children between 6 and 12 years old (inclusive) can
  ride it for half the cost, and children who are 5 years old or younger are
  free of charge. (Yen is the currency of Japan.)
  
  Find the cost of the Ferris wheel for Takahashi.
samples: [{"input": "30 100", "output": "100\n    \n\nTakahashi is 30 years old now, and the cost of the Ferris wheel is 100 yen.\n\n* * *"}, {"input": "12 100", "output": "50\n    \n\nTakahashi is 12 years old, and the cost of the Ferris wheel is the half of 100\nyen, that is, 50 yen.\n\n* * *"}, {"input": "0 100", "output": "0\n    \n\nTakahashi is 0 years old, and he can ride the Ferris wheel for free."}]