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 C++14 (GCC 5.4.1) (judge verdict: Accepted)

/* https://atcoder.jp/contests/abc104/tasks/abc104_c */

#include <iostream>
#include <vector>

int solve(int D, int G, std::vector<int> p, std::vector<int> c)
{
  int min_cnt_problem = 1e5;

  for (int mask = 0; mask < (1 << D); ++mask)
  {
    int sum_score = 0, cnt_problem = 0, idx_max_problem_score = -1;

    for (int i = 0; i < D; ++i)
    {
      if (mask >> i & 1)
      {
        sum_score += 100*(i + 1)*p.at(i) + c.at(i);
        cnt_problem += p.at(i);
      }
      else
      {
        idx_max_problem_score = i;
      }
    }

    if (sum_score < G)
    {
      int sub_problem_score = 100*(idx_max_problem_score + 1);
      int shortage_score = G - sum_score;

      int sub_cnt_problem = -1;
      for (int j = 1; j < p.at(idx_max_problem_score); ++j)
      {
        if (shortage_score <= sub_problem_score*j)
        {
          cnt_problem += j;
          sub_cnt_problem = j;
          break;
        }
      }

      if (sub_cnt_problem == -1)
      {
        continue;
      }
    }

    min_cnt_problem = std::min(min_cnt_problem, cnt_problem);
  }

  return min_cnt_problem;
}

int main(int argc, char *argv[])
{
  // Input
  int D, G;

  std::cin >> D >> G;

  std::vector<int> p(D);
  std::vector<int> c(D);

  for (int i = 0; i < D; ++i)
  {
    std::cin >> p.at(i) >> c.at(i);
  }

  // Output
  std::cout << solve(D, G, p, c) << std::endl;

  return 0;
}