using System;
using System.Collections.Generic;
using System.Globalization;
using System.IO.Pipes;

namespace cswork
{
    class Program
    {
        public Program() { }

        Scanner cin;
        const int MAXIN = 1024;
        bool[] used = new bool[MAXIN];
        int[] perm = new int[MAXIN];

        List<int[]> permList = new List<int[]>();

        void Omame()
        {
            cin = new Scanner();
            int d = cin.nextInt();
            long g = cin.nextLong();

            List<int[]> score = new List<int[]>();
            for (int i = 0; i < d; i++)
            {
                int[] array = new int[3];
                array[0] = (i + 1) * 100;
                array[1] = cin.nextInt();
                array[2] = array[0] * array[1] + cin.nextInt();
                score.Add(array);
            }

            int ans = int.MaxValue;
            for (int i = 0; i < 1 << d; i++)
            {
                long tmpG = 0;
                int count = 0;
                bool[] isSelected = new bool[d];
                for (int j = 0; j < d; j++)
                {
                    if ((i >> j & 1) == 1)
                    {
                        tmpG += score[j][2];
                        count += score[j][1];
                        isSelected[j] = true;
                    }
                }

                int nokoriIdx = -1;
                for (int j = d - 1; j >= 0; j--)
                {
                    if (!isSelected[j])
                    {
                        nokoriIdx = j;
                        break;
                    }
                }

                if (nokoriIdx != -1)
                {
                    for (int j = 0; j < score[nokoriIdx][1]; j++)
                    {
                        if (tmpG >= g)
                        {
                            break;
                        }
                        tmpG += score[nokoriIdx][0];
                        count++;
                    }
                }

                if (tmpG >= g)
                {
                    ans = Math.Min(ans, count);
                }
            }

            Console.WriteLine(ans);
        }


        static void Main(string[] args)
        {
            new Program().Omame();
        }

        public void Permutation(int pos, int n, int length)
        {
            if (pos == n)
            {
                permList.Add((int[])perm.Clone());
            }

            for (int i = 0; i < n; i++)
            {
                if (!used[i])
                {
                    perm[pos] = i;
                    used[i] = true;
                    Permutation(pos + 1, n, length);
                    used[i] = false;
                }
            }
        }
    }

    class Scanner
    {
        string[] s;
        int i;

        char[] cs = 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(cs, StringSplitOptions.RemoveEmptyEntries);
            i = 0;
            return next();
        }

        public int nextInt()
        {
            return int.Parse(next());
        }

        public long nextLong()
        {
            return long.Parse(next());
        }

        public double nextDouble()
        {
            return double.Parse(next());
        }
    }
}

Measured memory_bytes: 13268