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())
pc = [[int(i) for i in input().split()] for j in range(d)]

num = 2**d

score = 0
ans = 0

use = [0,1]

def nokori(use,score):
    tmp = 0
    for i in range(d):
        #print(use, d-1-i, d-1-i not in use)
        if d-1-i not in use:
            if pc[d-1-i][0] * (d-1-i+1) * 100 >= score:
                tmp += (score +(d-1-i+1) * 100 - 1) // ( (d-1-i+1) * 100 )
                return tmp
            elif pc[d-1-i][0] * (d-1-i+1) * 100 + pc[d-1-i][1] >= score:
                tmp += pc[d-1-i][0]
                return tmp
            else:
                tmp += pc[d-1-i][0]
                score -= pc[d-1-i][0] * (d-1-i+1) * 100 + pc[d-1-i][1]
kouho = []

kouho.append(nokori([-1],g))
#exit()

for i in range(num):
    use = []
    ans = 0
    score = 0
    cur = i
    #print(i)
    for j in range(d):
        if cur == 0:
            continue
        elif cur% 2 == 1:
            #print(i % 2,j)
            score += pc[j][0] * (j+1) * 100 + pc[j][1]
            ans += pc[j][0]
            use.append(j)
            #print(use,j,cur)
        #else:
            #cur -= 1
            #continue
        cur = cur // 2
    #print(use,i)
    if score >= g:
        kouho.append(ans)
    else:
        #print(use)
        #print(ans,score)
        kouho.append(ans+nokori(use,g-score))
        #print(ans+nokori(use,d-score))

#print(kouho)
kouho.sort()
print(kouho[0])