using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace AtCoder
{

    static class Program
    {
        static void Main()
        {
            int D;long G;
            Multi(out D, out G);
            var dif = new long[D][];
            for(int i = 0; i < D; i++)
            {
                dif[i]= GetLongArray();
            }

            long min = int.MaxValue;
            for(int bit = 0; bit < 1 << D; bit++)
            {
                long sum = 0;
                long num = 0;
                for(int i = 0; i < D; i++)
                {
                    if ((bit >> i & 1) == 1)
                    {
                        sum += dif[D - 1 - i][0] * (D - i) * 100 + dif[D - 1 - i][1];
                        num += dif[D - 1 - i][0];
                    }
                }
                if (sum < G)
                {
                    for (int i = 0; i < D; i++)
                    {
                        if ((bit >> i & 1) == 0)
                        {
                            num += Math.Min((long)Math.Ceiling((G - sum) * 1.0 / ((D - i) * 100)), dif[D - 1 - i][0]);
                            sum += Math.Min((long)Math.Ceiling((G - sum) * 1.0 / ((D - i) * 100)), dif[D - 1 - i][0]) * 100 * (D - i);

                            break;
                        }
                    }
                }
                if (sum >= G)
                {
                    min = Math.Min(min, num);
                }
            }

            Console.WriteLine(min);
            Console.ReadKey();
        }

        static void Solve()
        {

        }


        static public string GetStr() { return Console.ReadLine().Trim(); }
        static public int GetInt() { return int.Parse(Console.ReadLine()); }
        static public long GetLong() { return long.Parse(Console.ReadLine()); }
        static public string[] GetStrArray() { return Console.ReadLine().Split(' '); }
        static public int[] GetIntArray() { return Console.ReadLine().Split(' ').Select(int.Parse).ToArray(); }
        static public long[] GetLongArray() { return Console.ReadLine().Split(' ').Select(long.Parse).ToArray(); }
        static public char[] GetCharArray() { return Console.ReadLine().Split(' ').Select(char.Parse).ToArray(); }
        static public List<double> GetDoubleList() { return Console.ReadLine().Split(' ').Select(double.Parse).ToList(); }
        static public void WriteObjects<T>(IEnumerable<T> values) { foreach (var o in values) { Console.Write(o + " "); } }
        static string yesno(this bool b) { return b ? "yes" : "no"; }
        static string YesNo(this bool b) { return b ? "Yes" : "No"; }
        static string YESNO(this bool b) { return b ? "YES" : "NO"; }

        static bool eq<T, U>() => typeof(T).Equals(typeof(U));
        static T ct<T, U>(U a) => (T)Convert.ChangeType(a, typeof(T));
        static T cv<T>(string s) => eq<T, int>() ? ct<T, int>(int.Parse(s))
                           : eq<T, long>() ? ct<T, long>(long.Parse(s))
                           : eq<T, double>() ? ct<T, double>(double.Parse(s))
                           : eq<T, char>() ? ct<T, char>(s[0])
                                             : ct<T, string>(s);
        static void Multi<T>(out T a) => a = cv<T>(GetStr());
        static void Multi<T, U>(out T a, out U b)
        {
            var ar = GetStrArray(); a = cv<T>(ar[0]); b = cv<U>(ar[1]);
        }
        static void Multi<T, U, V>(out T a, out U b, out V c)
        {
            var ar = GetStrArray(); a = cv<T>(ar[0]); b = cv<U>(ar[1]); c = cv<V>(ar[2]);
        }
        static void Multi<T, U, V>(out T a, out U b, out V c, out V d)
        {
            var ar = GetStrArray(); a = cv<T>(ar[0]); b = cv<U>(ar[1]); c = cv<V>(ar[2]); d = cv<V>(ar[3]);
        }
    }
}

Measured memory_bytes: 13396