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 math
D,G=map(int,input().split())
PC=[list(map(int,input().split())) for i in range(D)]
zenkan=[]
def saiki(A):
    if len(A)==D:
        ans=0
        count=0
        toita=[]
        for i in range(D):
            if A[i]==1:
                ans+=PC[i][0]*(i+1)*100+PC[i][1]
                count+=PC[i][0]
                toita.append(i)
        zenkan.append([ans,count,toita])
        return ans
    for i in range(2):
        A.append(i)
        saiki(A)
        A.pop()
saiki([])
ans=[]
zenkan.sort()
for i in range(len(zenkan)):
    cost=zenkan[i][1]
    hituyo=G-zenkan[i][0]
    if zenkan[i][0]>=G:
        ans.append(cost)
        continue
    cost_kari=[]
    for j in range(D):
        if j not in zenkan[i][2]:
            if PC[j][0]*100*(j+1)>=hituyo:
                cost_kari.append(math.ceil(hituyo/(100*(j+1))))
            #print(math.ceil(hituyo/100*(j+1)),j)
    cost_kari.sort()
    if len(cost_kari)!=0:
        ans.append(cost+cost_kari[0])
    elif hituyo<=0:
        ans.append(cost)
    #print(cost_kari)
#print(zenkan)
#print(ans)
print(min(ans))