Problem:
Score : 300 points

Problem 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?

Constraints

1 ≤ D ≤ 10

1 ≤ p_i ≤ 100

100 ≤ c_i ≤ 10^6

100 ≤ G

All values in input are integers.

c_i and G are all multiples of 100.

It is possible to have a total score of G or more points.

Input

Input is given from Standard Input in the following format:

D G
p_1 c_1
:
p_D c_D

Output

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).

Sample Input 1

2 700
3 500
5 800

Sample Output 1

3

In this case, there are three problems each with 100 points and five problems each with 200 points. The perfect bonus for solving all the 100-point problems is 500 points, and the perfect bonus for solving all the 200-point problems is 800 points. Takahashi's objective is to have a total score of 700 points or more.

One way to achieve this objective is to solve four 200-point problems and earn a base score of 800 points. However, if we solve three 100-point problems, we can earn the perfect bonus of 500 points in addition to the base score of 300 points, for a total score of 800 points, and we can achieve the objective with fewer problems.

Sample Input 2

2 2000
3 500
5 800

Sample Output 2

7

This case is similar to Sample Input 1, but the Takahashi's objective this time is 2000 points or more. In this case, we inevitably need to solve all five 200-point problems, and by solving two 100-point problems additionally we have the total score of 2000 points.

Sample Input 3

2 400
3 500
5 800

Sample Output 3

2

This case is again similar to Sample Input 1, but the Takahashi's objective this time is 400 points or more. In this case, we only need to solve two 200-point problems to achieve the objective.

Sample Input 4

5 25000
20 1000
40 1000
50 1000
30 1000
1 1000

Sample Output 4

66

There is only one 500-point problem, but the perfect bonus can be earned even in such a case.

Solution in Ruby (2.3.3) (judge verdict: Accepted)

Grade = Struct.new(:point, :num, :bonus) do
  def total
    point * num + bonus
  end

  # required点が与えられて、その点を取るために必要な問題数を返す
  # ただし、全問とかないと届かない場合や全問解いても届かない場合は0を返す
  def required_num(required)
    d = (required + point - 1) / point
    if d < num
      d
    else
      0
    end
  end
end

def main
  g_num, target = ARGF.gets.split.map(&:to_i)
  grades = []
  g_num.times do |i|
    grades << Grade.new((i+1)*100, *ARGF.gets.split.map(&:to_i))
  end
  # pp grades

  min_num = 1000

  # bit mask の生成
  0.upto((1 << g_num) - 1) do |mask|
    # 各bitを下から舐める
    total = 0
    num = 0
    0.upto(g_num-1) do |i|
      # ビットが立っている＝全問解く
      if mask[i] == 1
        total += grades[i].total
        num += grades[i].num
      end

      # すでにmin_num以上の問題を解いている？➾試行を続ける意味なし
      break if min_num < num
    end

    # 得点が足りている場合はここでmin_numを更新
    if target <= total
      min_num = num if num < min_num
      next
    end

    # まだ得点が足りていなかったら、解いていない一番下の問題を解く
    # それでも足りない場合、それは全問回答する組み合わせが不適切ということ
    rest = target - total
    (g_num-1).downto 0 do |i|
      # iビット目が立っていない＝まだ解いていない
      if mask[i] == 0
        added_num = grades[i].required_num(rest)
        if 0 < added_num
          num += added_num
          min_num = num if num < min_num
        end
        break
      end
    end
  end

  puts min_num
end

if __FILE__ == $0
  main
end