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.Linq;//リストの使用
using System.Collections.Generic;
class Program
{
	static void Main()
	{
		string[] input = Console.ReadLine().Split(' ');
		long d = long.Parse(input[0]);
		long g = long.Parse(input[1]);
    long[,] vertexes = new long[d,2];
    long answer = long.MaxValue;
    long scoreMemo = 0;//得点
    long tookCountMemo = 0;//とった数
    for(long i = 0; i < d; i++)
    {
      long[] nums = Array.ConvertAll(Console.ReadLine().Split(' '),long.Parse);//１行ごとに受け取る
      vertexes[i,0] = nums[0];
      vertexes[i,1] = nums[1];
    }

    for(long i = 0; i < (1 << (int)d); i++)//bit全探索
    {
      scoreMemo = 0;
      tookCountMemo = 0;
      for(long checkDigit = 0; checkDigit < d; checkDigit++)//右からcheckDigit桁目を見る
      {
        if((i & (1<<(int)checkDigit)) != 0)//右からcheckDigit番目が1ならば
        {
          scoreMemo += vertexes[checkDigit,0]*(checkDigit+1)*100 + vertexes[checkDigit,1];
            //checkDigit番目はすべてとったと仮定
            tookCountMemo += vertexes[checkDigit,0];
        }
      }
      //Console.WriteLine(i + " " + scoreMemo + " " + tookCountMemo);
      if(scoreMemo >= g)
      {
        answer = Math.Min(answer, tookCountMemo);
      }
      else
      {
        for(long checkDigit = 0; checkDigit < d; checkDigit++)//右からcheckDigit桁目を見る
        {
          if((i & (1<<(int)checkDigit)) == 0)//右からcheckDigit番目が0ならば
          {
            if(g-scoreMemo <= (vertexes[checkDigit,0]-1)*(checkDigit+1)*100)
              //1種の追加で得点が可能ならば
            {
              long t = tookCountMemo + (g-scoreMemo+checkDigit*100) / ((checkDigit+1)*100);
              //Console.WriteLine(i + " " + scoreMemo + " " + t);
              answer = Math.Min(answer, t);
            }
          }
        }
      }
    }
    
		Console.WriteLine(answer);
	}
}