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.Runtime.Remoting.Contexts;

namespace Contest
{

    class Scanner
    {
        private string[] line = new string[0];
        private int index = 0;
        public string Next()
        {
            if (line.Length <= index)
            {
                line = Console.ReadLine().Split(' ');
                index = 0;
            }
            var res = line[index];
            index++;
            return res;
        }
        public int NextInt()
        {
            return int.Parse(Next());
        }
        public long NextLong()
        {
            return long.Parse(Next());
        }
        public string[] Array()
        {
            line = Console.ReadLine().Split(' ');
            index = line.Length;
            return line;
        }
        public int[] IntArray()
        {
            var array = Array();
            var result = new int[array.Length];
            for (int i = 0; i < array.Length; i++)
            {
                result[i] = int.Parse(array[i]);
            }

            return result;
        }
        public long[] LongArray()
        {
            var array = Array();
            var result = new long[array.Length];
            for (int i = 0; i < array.Length; i++)
            {
                result[i] = long.Parse(array[i]);
            }

            return result;
        }
    }

    class Program
    {
        private int D, G;
        private int[] p, c;
        private void Scan()
        {
            Scanner sc = new Scanner();
            D = sc.NextInt();
            G = sc.NextInt();
            p = new int[D];
            c = new int[D];
            for (int i = 0; i < D; i++)
            {
                p[i] = sc.NextInt();
                c[i] = sc.NextInt();
            }
        }


        public void Solve()
        {
            Scan();
            int loop = 1;
            for (int i = 0; i < D; i++)
            {
                loop *= 3;
            }

            int ans = int.MaxValue;
            for (int i = 0; i < loop; i++)
            {
                int cp = i;
                int cnt = 0;
                int score = 0;
                for (int j = D; j >= 1; j--)
                {
                    int sol = cp % 3;
                    if (sol == 0)
                    {
                        int max = (j * 100) * (p[j - 1] - 1);
                        if (G - score <= max)
                        {
                            int plus = (G - score + (j * 100) - 1) / (j * 100);
                            cnt += plus;
                            score += (j * 100) * plus;
                            break;
                        }
                        else
                        {
                            cnt += p[j - 1] - 1;
                            score += max;
                            if (score >= G)
                            {
                                break;
                            }
                        }
                    }
                    else if (sol == 1)
                    {
                        cnt += p[j - 1];
                        score += (j * 100) * p[j - 1] + c[j - 1];
                        if (score >= G)
                        {
                            break;
                        }
                    }
                    //Console.WriteLine($"{i} {score} {cnt}");

                    cp /= 3;
                }

                if (score >= G)
                {
                    //Console.WriteLine($"{i} {score} {cnt}");
                    ans = Math.Min(ans, cnt);
                }
            }
            Console.WriteLine(ans);
        }

        static void Main() => new Program().Solve();
    }
}