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 Python (3.4.3) (judge verdict: Wrong Answer)

from itertools import permutations, product
from math import ceil, floor

D, G = [int(elem) for elem in input().split(' ')]
point_info_list = [[int(elem) for elem in input().split()] for _ in range(D)]
assert len(point_info_list) == D
assert len(point_info_list[0]) == 2

# time complexity: O(D!)
""" min_num = float('inf')
for perm in permutations(range(D)):
    current_point = 0
    current_num = 0
    for point in perm:
        if (G - current_point) - (point + 1) * 100 * point_info_list[point][0] <= 0:
            current_num += ceil((G - current_point) / ((point + 1) * 100))
            break
        elif (G - current_point) - (point + 1) * 100 * point_info_list[point][0] - point_info_list[point][1] <= 0:
            current_num += point_info_list[point][0]
            break
        else:
            current_point += (point + 1) * 100 * point_info_list[point][0] + point_info_list[point][1]
            current_num += point_info_list[point][0]
    min_num = min(current_num, min_num)

print(min_num)
 """

# time complexity: O(D2^D)
min_num = float('inf')
for mask in product([False, True], repeat=D):
    chosen_indices = [i for i, chosen in enumerate(mask) if chosen]
    current_point = 0
    current_num_solved = 0
    for chosen_index in chosen_indices:
        point = (chosen_index + 1) * 100
        num_problems = point_info_list[chosen_index][0]
        bonus = point_info_list[chosen_index][1]
        current_point += point * num_problems + bonus
        current_num_solved += num_problems

    try:
        max_indice_of_the_others = max(set(range(D)) - set(chosen_indices))
    except ValueError:
        continue
    point = (max_indice_of_the_others + 1) * 100
    num_problems = point_info_list[max_indice_of_the_others][0]
    if (G - current_point) - point * num_problems > 0:
        continue
    elif G - current_point < 0:
        min_num = min(min_num, current_num_solved)
    else:
        current_num_solved += ceil((G - current_point) / point)
        min_num = min(min_num, current_num_solved)
print(min_num)