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;
using System.Collections.Generic;

class Cmondai
{
    static void Main()
    {
        var dg = Console.ReadLine().Split(' ').Select(x => Int64.Parse(x)).ToArray();
        var D = (int)dg[0];
        var G = dg[1];
        var list = new List<long[]>();
        for (int i=0;i<D;++i)
        {
            var pc= Console.ReadLine().Split(' ').Select(x => Int64.Parse(x)).ToArray();
            list.Add(new long[2] { pc[0], pc[1] });
        }
        var ans = long.MaxValue;
        for (int i = 0; i < (Math.Pow(2, D)); i++)
        {
            var count = 0L;
            var total = 0L;
            for (int j = 0; j < D; j++)
            {
                if ((1 & i >> j) == 1) {
                    count += list[j][0];
                    total += list[j][0] * 100 * (j + 1) + list[j][1];
                }
            }
            if (total < G)
            {
                for (int j = D - 1; 0 <= j; --j)
                {
                    if ((1 & i >> j) == 0)
                    {
                        var add = ((G-total)+((j + 1) * 100)-1) / ((j + 1) * 100);
                        if (add <= list[j][0])
                        {
                            count+=add;
                            total += add * 100 * (j + 1);
                            if (G <= total) ans = Math.Min(ans, count);
                        }
                        break;
                    }
                }
            }
            else ans=Math.Min(ans,count);
        }
        Console.WriteLine(ans);
    }
}