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# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Linq;
using System.Collections.Generic;

namespace myapp
{
    class AtCoder_abc104_c
    {
        const int QUESTION_COUNT = 0;
        const int BONUS_SCORE = 1;
        const int QUESTION_TOTAL_SCORE = 2;
        const int IS_SELECTED = 3;

        static int questionPatternCount = 0;
        static int targetScore = 0;
        static int currentBest = 1000;
        static int[][] questionArray;
        public static void Main()
        {

            int[] line1Array = Console.ReadLine().Split(' ').Select(number => int.Parse(number)).ToArray();
            questionPatternCount = line1Array[0];
            targetScore = line1Array[1];

            questionArray = new int[questionPatternCount][];
            for (int i = 0; i < questionPatternCount; i++)
            {
                int[] lineArray = Console.ReadLine().Split(' ').Select(number => int.Parse(number)).ToArray();
                questionArray[i] = new int[4];
                questionArray[i][QUESTION_COUNT] = lineArray[0];
                questionArray[i][BONUS_SCORE] = lineArray[1];
                questionArray[i][QUESTION_TOTAL_SCORE] = (100 * (i + 1) * questionArray[i][QUESTION_COUNT]) + questionArray[i][BONUS_SCORE];
                questionArray[i][IS_SELECTED] = 0;
            }

            RecursiveProcess(0, 1, 0, 0);
            RecursiveProcess(0, 0, 0, 0);

            Console.WriteLine(currentBest);
            return;
        }

        private static void RecursiveProcess(int depth, int isSelected, int totalScore, int totalQuestionCount)
        {
            if (depth > questionPatternCount - 1)
            {
                if (totalScore >= targetScore)
                {
                    if (totalQuestionCount < currentBest)
                    {
                        currentBest = totalQuestionCount;
                    }
                }
                else
                {
                    for (int scoreWeight = questionPatternCount; scoreWeight > 0; scoreWeight--)
                    {
                        if (questionArray[scoreWeight - 1][IS_SELECTED] == 1)
                        {
                            continue;
                        }

                        for (int questionNumber = 0; questionNumber < questionArray[scoreWeight - 1][QUESTION_COUNT]; questionNumber++)
                        {
                            totalScore += 100 * scoreWeight;
                            totalQuestionCount++;

                            if (questionNumber == questionArray[scoreWeight - 1][QUESTION_COUNT] - 1)
                            {
                                totalScore += questionArray[scoreWeight - 1][BONUS_SCORE];
                            }

                            if (totalScore >= targetScore)
                            {
                                if (totalQuestionCount < currentBest)
                                {
                                    currentBest = totalQuestionCount;
                                }
                            }
                        }
                    }
                }

                return;
            }

            if (isSelected == 1)
            {
                totalQuestionCount += questionArray[depth][QUESTION_COUNT];
                totalScore += questionArray[depth][QUESTION_TOTAL_SCORE];
            }

            questionArray[depth][IS_SELECTED] = isSelected;

            RecursiveProcess(depth + 1, 1, totalScore, totalQuestionCount);
            RecursiveProcess(depth + 1, 0, totalScore, totalQuestionCount);
        }
    }
}