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.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace __C__ProgramingContest
{
    class Program
    {
        static void Main(string[] args)
        {
            int num5 = 5;
            int num9 = 9;

            ////論理積
            //int numCalc = num5 & num9;

            //Console.Write(Convert.ToString(num5, 2).PadLeft(8, '0'));
            //Console.WriteLine("({0})", num5);

            //Console.Write(Convert.ToString(num9, 2).PadLeft(8, '0'));
            //Console.WriteLine("({0})", num9);

            //Console.WriteLine("{0} & {1} =", num5, num9);

            //Console.Write(Convert.ToString(numCalc, 2).PadLeft(8, '0'));
            //Console.WriteLine("({0})", numCalc);
            // 整数の入力
            //int a = int.Parse(Console.ReadLine());
            // スペース区切りの整数の入力
            string[] input = Console.ReadLine().Split(' ');
            int a = int.Parse(input[0]);
            int b = int.Parse(input[1]);
            // 100個の要素を0で初期化（intをnewした場合はゼロクリアされる）
            int[] x = new int[100005];
            int[] y = new int[100005];
            int[] z = new int[100005];
            int[,] count = new int[1003,1003];
            long QuestionNumberMax = 0;

            for (int i = 0; i < a; i++)
            {
                input = Console.ReadLine().Split(' ');
                x[i] = int.Parse(input[0]);
                y[i] = int.Parse(input[1]);
            }
            int ans = 100000000;
            for (int mask = 0; mask < (1 << a); ++mask)
            {
                int s = 0, num = 0, rest_max = -1;
                for (int i = 0; i < a; ++i)
                {
                    if((mask >>i&1)!=0)
                    {
                        s += 100 * (i + 1) * x[i] + y[i];
                        num += x[i];
                    }
                    else
                    {
                        rest_max = i;
                    }
                }
                if (s < b)
                {
                    int s1 = 100 * (rest_max + 1);
                    int need = (b - s + s1 - 1) / s1;
                    if (need >= x[rest_max])
                    {
                        continue;
                    }
                    num += need;
                }
                ans = Math.Min(ans, num);
            }



            //    for (int i = a - 1; i >= 0; i--)
            //    {
            //        for (int j = 0; j < x[i]; j++)
            //        {
            //            QuestionNumberMax++;
            //            z[QuestionNumberMax] = z[QuestionNumberMax - 1];
            //            z[QuestionNumberMax] += (i + 1) * 100;
            //            if (j == x[i] - 1)
            //            {
            //                z[QuestionNumberMax] += y[i];
            //            }
            //            if (z[QuestionNumberMax] >= b)
            //            {
            //                goto EndLoop;
            //            }
            //        }
            //    }
            //EndLoop:
            //for (int i = a-1; i >= 0; i++)
            //{
            //    for (int j = 0; j <= QuestionNumberMax; j++)
            //    {
            //        //z[j + x[i]] = Math.Max(z[j + x[i]], z[j] + (i + 1) * 100 * x[i] + y[i]);
            //        if (z[j + x[i]]< z[j] + (i + 1) * 100 * x[i] + y[i])
            //        {
            //            z[j + x[i]] = z[j] + (i + 1) * 100 * x[i] + y[i];
            //            break;
            //        }
            //    }
            //}
            //for (int i = 0; i < QuestionNumberMax; i++)
            //{
            //    if (z[i]>=b)
            //    {
            //        Console.WriteLine(i);
            //    }
            //}
            //for (int i = 0; i < QuestionNumberMax; i++)
            //{
            //    Console.WriteLine(z[i]);
            //}
            // 文字列の入力
            //string s = Console.ReadLine();
            //出力
            //Console.WriteLine((a + b) + " " + s);
            Console.WriteLine(ans);

        }
    }
}