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)

"
3. ABC104C - All Green
リンク：　https://atcoder.jp/contests/abc104/tasks/abc104_c
"

# 入力
D, G = gets.split.map(&:to_i)
p = []
c = []
D.times do |i|
  p[i], c[i] = gets.split.map(&:to_i)
end

# Dでbit全探索
# i桁目をp[i]進報で表せば、得点の計算できそう
ans = 100000
(1 << D).times do |i|
  point = 0
  ma = -1
  gap = 0
  num = 0
  tmp = 0
  D.times do |j|
    # i[j]==1なら配点100(j+1)の問題を完全に解く
    if i[j] == 1
      point = point + 100*(j+1) * p[j] + c[j]
      num = num + p[j]
      if point >= G
        ans = [ans, num].min
      end
    else
      ma = [ma, j].max
    end
  end
  # ここまでで全問解く配点の問題は決まった
  # 目標までの差を出す
  gap = G - point
  if ma != -1 && gap > 0
  # 完全に解かない(i[j]==0なるjの最大値)もののうち、
  # 最も高い配点はmaに入ってる配点100(ma+1)点 
    tmp = (gap.to_f / (100*(ma+1)).to_f).ceil #その配点を何問解けば目標達成できるか
    if tmp <= p[ma]-1 # これを満たさない場合は、完全に解く選択がミスってる
      # ここに入ったってことは、maの問題をnumだけ中途半端に解けば目標達成できる
      num = num + tmp
      ans = [ans, num].min
    end
  end
end
puts ans