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 ABC104
{
    class Program
    {
        static int D;
        static int G;
        static int[] p;
        static int[] c;

        static void Main(string[] args)
        {
            Init();
            Proc();
        }

        static void Init()
        {
            var DG = Read();
            D = DG[0];
            G = DG[1];
            p = new int[D];
            c = new int[D];

            for (int i = 0; i < D; i++)
            {
                var pc = Read();
                p[i] = pc[0];
                c[i] = pc[1];
            }
        }

        static void Proc()
        {
            int minCount = int.MaxValue;

            for (uint bit = 0; bit < (1 << D); bit++)
            {
                //Console.WriteLine($"===========================");
                int tempCount = 0;
                int tempPoint = 0;

                // 全問正解の得点を加算
                SumPointComplete(bit, ref tempPoint, ref tempCount);

                if (tempPoint < G)
                {
                    // 目標未達の場合は得点の高い問題から加算
                    AddPointMiddle(bit, ref tempPoint, ref tempCount);
                }

                // 必要正解数の最小値を更新
                minCount = Math.Min(tempCount, minCount);
            }

            Console.WriteLine(minCount);
            Console.ReadLine();
        }

        static void SumPointComplete(uint bit, ref int point, ref int count)
        {
            //Console.WriteLine(Convert.ToString(bit, toBase: 2));
            // ボーナスの組み合わせを全探索
            for (int i = 0; i < D; i++)
            {
                if (((bit >> i) & 1) == 1)
                {
                    // 全問正解分の得点
                    point += p[i] * (100 * (i + 1));
                    // ボーナス得点
                    point += c[i];
              
                    count += p[i];
                }
                //Console.WriteLine($"[all]point:{point}, count:{count}");
            }

        }

        static void AddPointMiddle(uint bit, ref int point, ref int count)
        {

            //Console.WriteLine($"[mid start]point:{point}, count:{count}");

            for (int k = (D - 1); k >= 0; k--)
            {
                if (((bit >> k) & 1) == 1)
                {
                    // XXX: 全問正解した問題も加算対象になっている
                    // FIX: 当該ケースをガード
                    continue;
                }

                int tempCount = 0;
                while (point < G && tempCount < p[k])
                {
                    point += (100 * (k + 1));
                    tempCount++;
                    count++;

                    //Console.WriteLine($"point:{point}, G:{G}, tempCount:{tempCount}, p[k]:{p[k]}");
                }
            }
            //Console.WriteLine($"[mid end]point:{point}, count:{count}");
        }

        static int[] Read()
        {
            return Console.ReadLine().Split(' ').Select(s => int.Parse(s)).ToArray();
        }
    }
}