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 AtCorder
{
    class Program
    {
        static void Main(string[] args)
        {

            //ABC104C
            var DG = ReadSplitInt();
            var D = DG[0];
            var G = DG[1];

            var pc = ReadSplitIntLines(D);
            var minCnt = int.MaxValue;

            for (int i = 0; i < (1 << D); i++)
            {
                var cnt = 0;
                var point = 0;

                // ボーナス取得可否判定
                for (int j = 0; j < D; j++)
                {
                    // piを完全回答
                    if ((i & (1 << j)) != 0)
                    {
                        point += (pc[j][0] * ((j + 1) * 100)) + pc[j][1];
                        cnt += pc[j][0];
                    }
                }

                if (point >= G)
                {
                    minCnt = Math.Min(minCnt, cnt);
                }
                else
                {
                    var doBreak = false;
                    for (int k = D - 1; 0 <= k; k--) 
                    {
                        if ((i & (1 << k)) == 0)
                        {
                            for (int l = 0; l < pc[k][0]; l++)
                            {
                                point += (100 * (k + 1));
                                cnt++;
                                if (point >= G)
                                {
                                    minCnt = Math.Min(minCnt, cnt);
                                    doBreak = true;
                                    break;
                                }
                            }
                        }
                        if (doBreak)
                        {
                            break;
                        }
                    }
                }
            }

            Console.WriteLine(minCnt);





            Console.ReadKey();
        }



        #region MyRegion

        public static int ReadInt()
        {
            return int.Parse(Console.ReadLine());
        }

        /// <summary>
        /// 空白区切の数値を取得する
        /// </summary>
        /// <returns>The read split int.</returns>
        public static int[] ReadSplitInt()
        {
            return Console.ReadLine().Split(' ').Select(x => int.Parse(x)).ToArray();
        }

        /// <summary>
        /// 空白区切の数値を取得
        /// </summary>
        /// <returns>The read split long.</returns>
        public static long[] ReadSplitLong()
        {
            return Console.ReadLine().Split(' ').Select(x => long.Parse(x)).ToArray();
        }


        public static int[][] ReadSplitIntLines(int n)
        {
            return Enumerable.Range(0, n).Select(x => ReadSplitInt()).ToArray();
        }

        public static long[][] ReadSplitLongLines(int n)
        {
            return Enumerable.Range(0, n).Select(x => ReadSplitLong()).ToArray();
        }

        public static long[][] ReadSplitLongLines(long n)
        {
            var ret = new List<long[]>();
            for (long i = 0; i < n; i++)
            {
                ret.Add(ReadSplitLong().ToArray());
            }

            return ret.ToArray();
        }

        #endregion

    }
}