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;

namespace ABC104C
{
    static class MainClass
    {

        public static void Main(string[] args)
        {


            string[] input1 = Console.ReadLine().Split(' ');
            int D = int.Parse(input1[0]);
            int G = int.Parse(input1[1]);
            var plst = new List<int>();
            var clst = new List<int>();
            var RestDlst = new List<int>();
            var Dmemolst = new List<int>();
            int p = 0;
            int c = 0;
            for (int i = 0; i < D; i++) {
                string[] input2 = Console.ReadLine().Split(' ');
                p = int.Parse(input2[0]);
                c = int.Parse(input2[1]);
                plst.Add(p);
                clst.Add(c);
                RestDlst.Add(i+1);
                Dmemolst.Add(p * (i + 1) * 100 + c);
           }
            int ans = 1000000000;
            
            for (int mask = 0; mask < (1 << D); mask++)
            {

                int pt = 0, restmax = -1,num=0;
                
                //その0101...でのptを計算
                for(int i = 0; i < D; i++)
                {
                    //Console.WriteLine("mask: " + mask.ToString() + " maskbit: " + (mask>>1).ToString());
                    if (((mask >> i) & 1)==1)
                    {
                        pt += 100 * (i + 1) * plst[i] + clst[i];
                        num += plst[i];
                    }
                    else
                    {
                        restmax = i;
                    }
                }
                //Gに達していなければ、restmaxを中途半端に解く
                if (pt < G)
                {
                    //restmaxの1問あたりの点数
                    int ptrmx = 100 * (restmax + 1);
                    int neednum = (G - pt + ptrmx - 1) / ptrmx;
                    //必要な問題数がp[restmax]を超えてしまったらその0100...はボツ
                    if(neednum > plst[restmax])
                    {
                        continue;
                    }
                    num += neednum;
                }
                ans = Math.Min(ans, num);
            }

            Console.WriteLine(ans);


            return;


        }


        public static int Dfs(int p, int D, List<int> plst, List<int> clst, List<int> RestDlst, int N, int G,List<int> Dmemolst)
        {

            if (p >= G)
            {
                return N;
            }
            if (Dmemolst[D - 1] + p < G)
            {
                p = p + Dmemolst[D - 1];
                N += plst[D - 1];
            }
            else {
                for (int i = 0; i < plst[D - 1]; i++)
                {
                    p = p + 100 * D;
                    N++;
                    if (p >= G) {
                        return N;
                    }
                }
                p += clst[D - 1];
            } 
            if (p >= G)
            {
                return N;
            }
            var anslst = new List<int>();
            foreach(int item in RestDlst)
            {
                var tmpRDlst = new List<int>(RestDlst);
                tmpRDlst.Remove(item);
                anslst.Add(Dfs(p, item, plst, clst, tmpRDlst, N, G,Dmemolst));
            }
            return anslst.Min();
        }



        public static long Gcd(long a, long b)
        {
            long tmp;
            // a<bにする
            if (a >= b)
            {
                tmp = a;
                a = b;
                b = tmp;
            }

            if (a == 0)
            {
                return b;
            }

            tmp = a;
            a = b % a;
            b = tmp;
            return Gcd(a, b);

        }


        public static IEnumerable<long> PF(long n)
        {
            long i = 2;
            long tmp = n;

            while (i * i <= n) //※1
            {
                if (tmp % i == 0)
                {
                    tmp /= i;
                    yield return i;
                }
                else
                {
                    i++;
                }
            }
            if (tmp != 1) yield return tmp;//最後の素数も返す
        }




    }

}