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)

#include <bits/stdc++.h>
using namespace std;

void searchMinProbNum(vector<int> &p, vector<long>& c, int &minProbNum, int tmpProbNum, int goal, int const D) {
  
  for (int i = 0; i < D; i++) {
    int tmp = p.at(i);
    if (tmp == 0) {
      continue;
    }
    
    int point = tmp * (i + 1) + c.at(i);
    if (goal <= point) {
      point = 0;
      int j = 1;
      while (j < tmp) {
        point += (i + 1);
        if (goal <= point) {
          break;
        }
        j++;
      }
      minProbNum = min(tmpProbNum + j, minProbNum);
      //cout << i << " " << probNum << endl;
      continue;
    }
    
    if (tmpProbNum + tmp >= minProbNum) {
      continue;
    } else {
      p.at(i) = 0;
      searchMinProbNum(p, c, minProbNum, tmpProbNum + tmp, goal - point, D);
      p.at(i) = tmp;
    }
  }
}  

int main() {
  int D;
  long long G;
  cin >> D >> G;
  G /= 100;
  
  vector<int> p(D);
  vector<long> c(D);
  for (int i = 0; i < D; i++) {
    long b;
    cin >> p.at(i) >> b;
    c.at(i) = b / 100; 
  }
  
  int minProbNum = 1000;
  searchMinProbNum(p, c, minProbNum, 0, G, D);
  cout << minProbNum;
}