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: Wrong Answer)

using System;
using System.Collections.Generic;
//using System.Linq;
class Program
{
  //static List<string> list;
	static void Main(string[] args)
	{
		// 入力フェーズ
        string[] input = Console.ReadLine().Split(' ');
        int D = int.Parse(input[0]);
        int G = int.Parse(input[1]);
        int[,] table = Input(D);

        // 問題の合計数は・・・
        int totalProb = getTotalProblemCount(table);

//Console.WriteLine("total:" + totalProb);
        int outerI = 0;
        for(int i=1; i<=totalProb; i++)
        {
          // 合計i問解いた時の最大得点は・・・
          int[,] copy = new int[2,D];
          Array.Copy(table, copy, table.Length);
          int point = getMaxPoint(i, copy);
  //Console.WriteLine(i + " 問といた　" + point);
          if(point >= G)
          {
            outerI = i;
            break;
          }
        }
    // 出力
        Console.WriteLine(outerI);
    }
		class myClass{ //自作クラス
			public int ID {set; get;}
			public long Point {set; get;}
		}
    static private int getMaxPoint(int solve, int[,] table)
    {
      int ret = 0;
      // 合計solve問解いた時の点数の最大値は・・・
      //Console.WriteLine(solve + " もんとく");
      while(solve>0)
      {
        int maxPoint = 0, maxS = 1, maxI = 0;
        for(int i=0; i<table.GetLength(1); i++)
        {
          // i問目はもう全問解いた・・・
          if(table[0,i] == 0) continue;
          // i問目を解くと・・・
          int point = 0, s=0;
          //Console.WriteLine(i + "問目は" + table[0,i] + "問ある ボーナスは" + table[1,i] );
          if(solve >= table[0,i])
          {
            // 全問解ける
            point = table[0,i] * (i+1) * 100 + table[1,i];
            s = table[0,i];
          }
          else
          {
            // 全問は解けない
            point = solve * (i+1) * 100;
            s = solve;
          }

          // 他の問題との効率を比較
          if(maxS > 0 && s > 0 && (decimal)maxPoint/maxS < (decimal)point/s)
          {
            //Console.WriteLine("比較 " + maxPoint + " / " + maxS + " " + point + " / " + s);

            maxPoint = point;
            maxS = s;
            maxI = i;
          }
        }
        //Console.WriteLine(maxS + "問解いた " + maxI + "番目の問題　 " + maxPoint + "点");
        ret += maxPoint;
        solve -= maxS;
        table[0,maxI] -= maxS;
      }
      return ret;
    }

    static private int getTotalProblemCount(int[,] table)
    {
      int ret = 0;
      //Console.WriteLine(table.GetLength(1) + "ながさ");
      for(int i=0; i<table.GetLength(1); i++)
      {
        ret += table[0, i];
      }
      return ret;
    }

    static private int[,] Input(int D)
    {
      int [,] table = new int[2,D];
      for(int i=0; i<D;i++)
      {
        string[] input = Console.ReadLine().Split(' ');
        table[0, i] = int.Parse(input[0]);
        table[1, i] = int.Parse(input[1]);
      }
      return table;
    }

}