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)

D, G = gets.split.map(&:to_i)
pc_list = D.times.map { gets.split.map(&:to_i) }
MAX = 1 << 60
ans = MAX
(0...(2 ** D)).each do |bs|
  ret = (0...D).reduce([0, 0]) do |acc, d|
    if bs[d] == 0
      acc
    else
      # ボーナスを獲得する
      count = pc_list[d][0]
      bonus = pc_list[d][1]
      total_count = acc[0] + count
      total_point = acc[1] + ((d + 1) * 100 * count) + bonus
      [total_count, total_point]
    end
  end
  count = ret[0]
  point = ret[1]
  if point >= G
    ans = [ans, count].min
  else
    # 必要な点数に満たない
    rest_point = (G - point)
    d = (D - 1).downto(0).find do |d|
      bs[d] == 0
    end
    next unless d
    max_d_count = [pc_list[d][0] - 1, 0].max
    d_unit = ((d + 1) * 100)
    d_count = rest_point % d_unit == 0 ? rest_point / d_unit : rest_point / d_unit + 1
    if max_d_count >= d_count
      ans = [ans, count + d_count].min
    end
  end
end
puts ans