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)

#pragma warning disable

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.Serialization.Formatters.Binary;
using System.Text;
using System.Text.RegularExpressions;
using System.Diagnostics;
using System.Numerics;
using System.Collections;

static class MainClass
{
    public static void Main(string[] args)
    {
        var DG = Console.ReadLine().SplittedStringToInt32List();
        var D = DG[0];
        var G = DG[1];

        var problems = new List<KeyValuePair<int, int>>();

        for (int i = 0; i < D; i++)
        {
            var pc = Console.ReadLine().SplittedStringToInt32List();
            var p = pc[0];
            var c = pc[1];
            problems.Add(new KeyValuePair<int, int>(p, c));
        }
        
        var bits = CreateBits(D).Where(x => x.Count(_ => _ == null) == 1);
        var mincount = INF;
        foreach (var item in bits)
        {
            var count = 0;
            var sum = 0;
            var nullind = -1;
            for (int i = 0; i < D; i++)
            {
                if (item[i] == null)
                {
                    nullind = i;
                }
                else if (item[i] == true)
                {
                    count += problems[i].Key;
                    sum += problems[i].Value + (i + 1) * 100 * problems[i].Key;
                }
            }
            if (sum >= G)
            {
                mincount = Math.Min(count, mincount);
            }
            else
            {
                var rem = G - sum;
                if (G - sum > (nullind + 1) * 100 * problems[nullind].Key + problems[nullind].Value)
                {
                    continue;
                }
                else
                {
                    if (G - sum <= (nullind + 1) * 100 *(problems[nullind].Key - 1))
                    {
                        count += (G - sum) / (100 * (nullind + 1)) + (((G - sum) % (100 * (nullind + 1)) == 0) ? 0:1);
                    }
                    else
                    {
                        count += problems[nullind].Key;
                    }
                }
                mincount = Math.Min(mincount, count);
            }
        }
        Console.WriteLine(mincount);

        Console.ReadLine();
    }


    public static List<List<bool?>> CreateBits(int len)
    {
        return CreateBitsPri(new List<List<bool?>>(), len, 0);
    }

    private static List<List<bool?>> CreateBitsPri(List<List<bool?>> bits, int len, int count)
    {
        if (count == 0)
        {
            var lss = new List<bool?>();
            lss.Add(true);
            bits.Add(lss);
            var lx = new List<bool?>();
            lx.Add(false);
            bits.Add(lx);
            var lxx = new List<bool?>();
            lxx.Add(null);
            bits.Add(lxx);
            count++;
            return CreateBitsPri(bits, len, count);
        }
        if (len - count == 0)
            return bits;
        count++;
        var ls = new List<List<bool?>>();
        foreach (var item in bits)
        {
            var x = item.ToList();
            var y = item.ToList();
            x.Add(true);
            item.Add(false);
            y.Add(null);
            ls.Add(item);
            ls.Add(x);
            ls.Add(y);
        }
        return CreateBitsPri(ls, len, count);
    }
    

    #region ライブラリ
    public static long ToInt64(this string str) => long.Parse(str);
    public static int ToInt32(this string str) => int.Parse(str);
    public static BigInteger ToBigInteger(this string str) => BigInteger.Parse(str);
    public static List<string> SplittedStringToList(this string str) => str.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries).ToList();
    public static List<int> SplittedStringToInt32List(this string str) => str.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries).Select(x => int.Parse(x)).ToList();
    public static List<long> SplittedStringToInt64List(this string str) => str.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries).Select(x => long.Parse(x)).ToList();
    public static List<BigInteger> SplittedStringToBigInteger(this string str) => str.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries).Select(x => BigInteger.Parse(x)).ToList();
    public const int INF = int.MaxValue / 2;
    public const long LONGINF = long.MaxValue / 2;
    
  
  

    public static void PrintArray(int[,] array)
    {
        for (int i = 0; i < array.GetLength(0); i++)
        {
            var sb = new StringBuilder();
            for (int j = 0; j < array.GetLength(1); j++)
            {
                sb.Append(array[i, j]).Append(" ");
            }
            Console.WriteLine(sb.ToString());
        }
    }

    #endregion
}