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)

d, g = map(int,input().split())
plist = [list(map(int,input().split())) for i in range(d)]

# map of {number of problems to achieve ps : ps}
basiclist = []

for i in range(len(plist)):
    tmplist = [plist[i][0], (plist[i][0])*(i+1)*100+plist[i][1]]
    # problem.append(plist[i][0])
    basiclist.append(tmplist)

# combination of perfect score cases: ps0, ps1, ps2, ps0 + ps1, ...
import itertools

problem = [i for i in range(d)]

combs = []

for i in range(1, d+1):
    els = [list(x) for x in itertools.combinations(problem, i)]
    # print(els)
    combs.extend(els)


mincount = 2**10+1

# case without perfect score
for i in range (d):
    for j in range (1, basiclist[i][0]):
        if j*(i+1)*100 >= g:
            mincount = min(mincount, j)

# case of with perfect score
for comb in combs:
    # find the best-valued question that is not in the combination
    best_remaining_num = -1
    for a in range(d):
        if a not in comb:
            best_remaining_num = max(a, best_remaining_num)
    best_remaining_score = (best_remaining_num+1)*100

    # total perfect score of the combination and attempts required to achieve the score
    total_ps = 0
    total_ps_count = 0
    for com in comb:
        total_ps += basiclist[com][1]
        total_ps_count += basiclist[com][0]

    if best_remaining_num == -1:
        mincount = min(mincount, total_ps_count)
        continue

# case ps comb + remaining best-valued question*0, ..., ps comb + remaining best-valued question*(max possible -1)
    for i in range(basiclist[best_remaining_num][0]):
        if total_ps + best_remaining_score*i >= g:
            # print(comb, total_ps_count, total_ps, best_remaining_score, i, total_ps + best_remaining_score * i)
            mincount = min(mincount, i + total_ps_count)
            # print(mincount)
            break

print(mincount)