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;

class Main{
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		int D=sc.nextInt();
		int G=sc.nextInt();
		int[][] prbs=new int[D][2];
		int[] toki=new int[D];
		for(int i=0; i<D; i++) {
			prbs[i][0]=sc.nextInt();
			prbs[i][1]=sc.nextInt();
		}

		int brute=1;
		for(int i=0; i<D; i++) {
			brute*=2;
			toki[i]=0;
		}
		int tmp=0;
		int mondaisu=0;
		int min=Integer.MAX_VALUE;
		for(int i=0; i<brute; i++) {
			tmp=0;
			mondaisu=0;
			int a=i;
			for(int j=0; j<D; j++) {
				tmp+=(a%2)*((j+1)*100*prbs[j][0]+prbs[j][1]);
				mondaisu+=prbs[j][0]*(a%2);
				toki[j]=a%2;
				a/=2;
			}
			if(tmp>=G) {
				min=Math.min(min,mondaisu );
			}
			else if(tmp<G){
				int sabun=G-tmp;
				for(int j=0; j<D; j++) {
					if(toki[j]==0) {
						int tuika=Math.min((sabun+(j+1)*100-1)/((j+1)*100), prbs[j][0]);
						if(sabun<=tuika*(j+1)*100) {
							min=Math.min(min, mondaisu+tuika);
						}
					}
				}
			}
		}
		System.out.println(min);
	}
}