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: Time Limit Exceeded)

using System;
using System.Linq;

namespace AtCoder.Problems
{
    public class ProblemAbc079C
    {
        public static void Main(string[] args)
        {
            var s = new Solve079C();
            s.Solve();
        }

        public class Scanner
        {
            private string[] _s;
            private int _i;
            private readonly char[] _separators = new char[] {' '};

            public Scanner()
            {
                _s = new string[0];
                _i = 0;
            }

            public string Next()
            {
                if (_i < _s.Length) return _s[_i++];
                string st = Console.ReadLine();
                while (st == "") st = Console.ReadLine();
                _s = st.Split(_separators, StringSplitOptions.RemoveEmptyEntries);
                if (_s.Length == 0) return Next();
                _i = 0;
                return _s[_i++];
            }

            public int NextInt() => int.Parse(Next());
            public long NextLong() => long.Parse(Next());
            public ulong NextULong() => ulong.Parse(Next());
            public double NextDouble() => double.Parse(Next());

            public int[] GetIntArray(int n, int add = 0)
            {
                int[] array = new int[n];
                for (int i = 0; i < n; i++)
                {
                    array[i] = NextInt() + add;
                }
                return array;
            }

            public long[] GetLongArray(int n, long add = 0)
            {
                long[] array = new long[n];
                for (int i = 0; i < n; i++)
                {
                    array[i] = NextLong() + add;
                }
                return array;
            }

            public double[] GetDoubleArray(int n, double add = 0)
            {
                double[] array = new double[n];
                for (int i = 0; i < n; i++)
                {
                    array[i] = NextDouble() + add;
                }
                return array;
            }
        }
    }

    public class Solve079C
    {
        public void Solve()
        {
            var cin = new ProblemAbc079C.Scanner();
            var d = cin.NextInt();
            var g = cin.NextInt();
            var p = new int[d];
            var c = new int[d];
            for (int i = 0; i < d; i++)
            {
                p[i] = cin.NextInt();
                c[i] = cin.NextInt();
            }

            var result = GetAnswer(d, g, p, c);
            Console.WriteLine(result);
        }

        private int _d;
        private int _g;
        private int[] _p;
        private int[] _c;

        public int GetAnswer(int d, int g, int[] p, int[] c)
        {
            _d = d;
            _g = g;
            _p = p;
            _c = c;

            var max = p.Sum();
            for (int ans = 1; ans <= max; ans++)
            {
                if (dfs(0, ans, 0)) { return ans; }
            }
            return -1;
        }

        private bool dfs(int i, int remain, int sum)
        {
            if (remain == 0 || i >= _d) { return sum >= _g; }

            var max = Math.Min(remain, _p[i]);
            for (int j = 0; j <= max; j++)
            {
                var v = 100 * (i + 1) * j;
                if (_p[i] == j) { v += _c[i]; }
                if (dfs(i + 1, remain - j, sum + v)) { return true; }
            }

            return false;
        }
    }
}