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: Accepted)

import itertools
import math
d,g = map(int,input().split())
lis = [list(map(int,input().split())) for _ in range(d)]
# print(list(itertools.product([0,1], repeat=d))) [(0, 0), (0, 1), (1, 0), (1, 1)]
count_list = []
for flag in itertools.product([0,1], repeat=d):
    tmp = g
    count = 0
    score_list = []
    kosuu_list = []
    for i,f in enumerate(flag):
        if f==1:
            count += lis[i][0]
            #print(lis[i][1],100*(i+1),lis[i][0],tmp)
            tmp -= (lis[i][1]+100*(i+1)*lis[i][0])
        else:
            score_list.insert(0,100*(i+1))
            kosuu_list.insert(0,lis[i][0]-1)
    #print(score_list)
    #print(kosuu_list)
    #print(lis[i][1],100*(i+1),lis[i][0],tmp)
    if tmp <= 0:
        count_list.append(count)
    else:
        for sss,kkk in zip(score_list,kosuu_list):
            if tmp <= 0:
                break
            elif sss*kkk >= tmp:
                count += math.ceil(tmp/sss)
                tmp -= sss*math.ceil(tmp/sss)
                break
            elif sss*kkk < tmp:
                count += kkk
                tmp -= sss*kkk
        if tmp <= 0:
            count_list.append(count)
    #print(flag)
#print(count_list)
print(min(count_list))