output_description: Print the minimum total number of attacks required to vanish the monster.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N H
      a_1 b_1
      :
      a_N b_N
attempt: import math as m1
  n, h = map(int, input().split())
  a, b = [], []
  for i in range(n):
      a_, b_ = map(int, input().split())
      a.append(a_)
      b.append(b_)
  b = list(reversed(sorted(b)))
  m = max(a)
  ans = 0
  for i in b:
      if i > m:
          if h - i <= 0:
              print(ans + 1)
              exit()
          h -= i
          ans += 1
      if 
  print(ans + m1.ceil(h / m))
problem_description: Statement
  
  You are going out for a walk, when you suddenly encounter a monster.
  Fortunately, you have N katana (swords), Katana 1, Katana 2, …, Katana N, and
  can perform the following two kinds of attacks in any order:
  
    * Wield one of the katana you have. When you wield Katana i (1 ≤ i ≤ N), the monster receives a_i points of damage. The same katana can be wielded any number of times.
    * Throw one of the katana you have. When you throw Katana i (1 ≤ i ≤ N) at the monster, it receives b_i points of damage, and you lose the katana. That is, you can no longer wield or throw that katana.
  
  The monster will vanish when the total damage it has received is H points or
  more. At least how many attacks do you need in order to vanish it in total?
samples: [{"input": "1 10\n    3 5", "output": "3\n    \n\nYou have one katana. Wielding it deals 3 points of damage, and throwing it\ndeals 5 points of damage. By wielding it twice and then throwing it, you will\ndeal 3 + 3 + 5 = 11 points of damage in a total of three attacks, vanishing\nthe monster.\n\n* * *"}, {"input": "2 10\n    3 5\n    2 6", "output": "2\n    \n\nIn addition to the katana above, you also have another katana. Wielding it\ndeals 2 points of damage, and throwing it deals 6 points of damage. By\nthrowing both katana, you will deal 5 + 6 = 11 points of damage in two\nattacks, vanishing the monster.\n\n* * *"}, {"input": "4 1000000000\n    1 1\n    1 10000000\n    1 30000000\n    1 99999999", "output": "860000004\n    \n\n* * *"}, {"input": "5 500\n    35 44\n    28 83\n    46 62\n    31 79\n    40 43", "output": "9"}]