output_description: Print the minimum number of problems that needs to be solved in order to have
  a total score of G or more points. Note that this objective is always
  achievable (see Constraints).
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      D G
      p_1 c_1
      :
      p_D c_D
attempt: n, g = map(int, input().split())
  standard = []
  bonus = []
  num_of_problems = []
  for i in range(n):
      a, b = map(int, input().split())
      standard.append(a * (i + 1) * 100)
      bonus.append(b)
      num_of_problems.append(a)
  points_after_completion = []
  min_num = 10 * 100
  for i in range(2**n):
      point = 0
      num = 0
      li = list(range(n))
      for j in range(n):
          if (i >> j) & 1:
              point += standard[n - j - 1] + bonus[n - j - 1]
              num += num_of_problems[n - j - 1]
              li.remove(n - j - 1)
      counter = 0
      if li != []:
          while point < g and counter <= num_of_problems[li[-1]]:
              point += 100 * (li[-1] + 1)
              num += 1
              counter += 1
      if num < min_num and point >= g:
          min_num = num
  print(min_num)
  
problem_description: Statement
  
  A programming competition site _AtCode_ provides algorithmic problems. Each
  problem is allocated a score based on its difficulty. Currently, for each
  integer i between 1 and D (inclusive), there are p_i problems with a score of
  100i points. These p_1 + … + p_D problems are all of the problems available on
  AtCode.
  
  A user of AtCode has a value called _total score_. The total score of a user
  is the sum of the following two elements:
  
    * Base score: the sum of the scores of all problems solved by the user.
    * Perfect bonuses: when a user solves all problems with a score of 100i points, he/she earns the perfect bonus of c_i points, aside from the base score (1 ≤ i ≤ D).
  
  Takahashi, who is the new user of AtCode, has not solved any problem. His
  objective is to have a total score of G or more points. At least how many
  problems does he need to solve for this objective?
samples: [{"input": "2 700\n    3 500\n    5 800", "output": "3\n    \n\nIn this case, there are three problems each with 100 points and five problems\neach with 200 points. The perfect bonus for solving all the 100-point problems\nis 500 points, and the perfect bonus for solving all the 200-point problems is\n800 points. Takahashi's objective is to have a total score of 700 points or\nmore.\n\nOne way to achieve this objective is to solve four 200-point problems and earn\na base score of 800 points. However, if we solve three 100-point problems, we\ncan earn the perfect bonus of 500 points in addition to the base score of 300\npoints, for a total score of 800 points, and we can achieve the objective with\nfewer problems.\n\n* * *"}, {"input": "2 2000\n    3 500\n    5 800", "output": "7\n    \n\nThis case is similar to Sample Input 1, but the Takahashi's objective this\ntime is 2000 points or more. In this case, we inevitably need to solve all\nfive 200-point problems, and by solving two 100-point problems additionally we\nhave the total score of 2000 points.\n\n* * *"}, {"input": "2 400\n    3 500\n    5 800", "output": "2\n    \n\nThis case is again similar to Sample Input 1, but the Takahashi's objective\nthis time is 400 points or more. In this case, we only need to solve two\n200-point problems to achieve the objective.\n\n* * *"}, {"input": "5 25000\n    20 1000\n    40 1000\n    50 1000\n    30 1000\n    1 1000", "output": "66\n    \n\nThere is only one 500-point problem, but the perfect bonus can be earned even\nin such a case."}]