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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.util.Scanner;
import java.util.Arrays;

class Main {
    public static void main(String... args) {
        int D = IN.nextInt();
        int G = IN.nextInt();
        int[] p = new int[D + 1];
        int[] c = new int[D + 1];
        // pad index 0
        for (int i = 1; i <= D; i++) {
            p[i] = IN.nextInt();
            c[i] = IN.nextInt();
        }
        int[] complete = new int[D + 1];
        for (int i = 1; i <= D; i++) {
            complete[i] = 100 * i * p[i] + c[i];
        }
        int ans = Integer.MAX_VALUE;
        for (int i = 0; i < (1 << D); i ++) {
            int score = 0;
            int num = 0;
            for (int j = 1; j <= D; j++) {
                int k = 1 << (j - 1);
                if ((i & k) > 0) {
                    score += complete[j];
                    num += p[j];
                }
            }
            if (score >= G) {
                ans = num < ans ? num : ans;
            } else {
                int notCompInd = 0;
                for (int m = 0; m < D; m++) {
                    if (((~i >> m) & 1) == 1) {
                        notCompInd = m + 1;
                    }
                }
                if (notCompInd == 0) {
                    continue;
                }
                int solvNum = (G - score) / (notCompInd * 100);
                if (((G - score) % (notCompInd * 100)) > 0) {
                    solvNum++;
                }
                if (solvNum > (p[notCompInd] - 1)) {
                    continue;
                }
                num += solvNum;
                ans = num < ans ? num : ans;
            }
        }
        puts(ans);
    }

    static final Scanner IN = new Scanner(System.in);
    static <T> void puts(T arg) { System.out.println(arg); }
}