using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace Competitive
{
    internal class Solution
    {
        public int D, G;
        public int[] P, C;
        public int ret;
        public void Run()
        {
            {
                var line = Input.ReadIntArray();
                D = line[0];
                G = line[1];
            }

            P = new int[D];
            C = new int[D];
            for (int i = 0; i < D; i++)
            {
                var line = Input.ReadIntArray();
                P[i] = line[0];
                C[i] = line[1];
            }

            // ビット列の生成
            ret = int.MaxValue;
            var bf = new BruteForceBit(D, Process);
            bf.DFSRun();

            // 終了処理
            Console.WriteLine(ret);
        }

        public void Process(bool[] F)
        {
            int c = 0;
            int p = 0;
            for (int i = 0; i < F.Length; i++)
            {
                if (F[i])
                {
                    c += P[i];
                    p += P[i] * (i + 1) * 100 + C[i];
                }
            }

            for (int i = F.Length - 1; i >= 0; i--)
                if(!F[i])
                {
                    int ps = P[i];
                    while (ps > 0 && p < G)
                    {
                        ps--;
                        c += 1;
                        p += (i + 1) * 100;
                    }
                }

            if (p < G) c = int.MaxValue;

            ret = Math.Min(ret, c);
        }
    }


    // libs ----------
    class BruteForceBit
    {
        public int N;
        public bool[] F;
        private Action<bool[]> Process;

        public BruteForceBit(int N, Action<bool[]> process)
        {
            this.N = N;
            F = new bool[N];
            Process = process;
        }

        public void DFSRun()
        {
            DFS(0);
        }

        private void DFS(int i)
        {
            if (i == N)
            {
                Process(F);
            }
            else
            {
                F[i] = true;
                DFS(i + 1);
                F[i] = false;
                DFS(i + 1);
            }
        }

    }

    // common ----------

    internal static class Input
    {
        public static string ReadString()
        {
            string line = Console.ReadLine();
            return line;
        }

        public static int ReadInt()
        {
            string line = Console.ReadLine();
            return int.Parse(line);
        }

        public static int[] ReadIntArray()
        {
            string line = Console.ReadLine();
            return line.Split(' ').Select(int.Parse).ToArray();
        }

        public static long ReadLong()
        {
            string line = Console.ReadLine();
            return long.Parse(line);
        }

        public static long[] ReadLongArray()
        {
            string line = Console.ReadLine();
            return line.Split(' ').Select(long.Parse).ToArray();
        }

        public static double[] ReadDoubleArray()
        {
            string line = Console.ReadLine();
            return line.Split(' ').Select(double.Parse).ToArray();
        }
    }

    internal class Program
    {
        public static void Main(string[] args)
        {
            var s = new Solution();
            s.Run();
        }
    }
}

Measured memory_bytes: 13396