using System;

namespace ABC104C
{
    class Program
    {
        static void Main(string[] args)
        {
            var DG = Console.ReadLine().Split(' ');
            var D = int.Parse(DG[0]);
            var G = int.Parse(DG[1]);
            var problems = new Problem[D];
            for (var i = 0; i < D; i++)
            {
                var pci = Console.ReadLine().Split(' ');
                var pi = int.Parse(pci[0]);
                var ci = int.Parse(pci[1]);
                problems[i] = new Problem(
                    difficulty: i + 1,
                    count: pi,
                    completeBonus: ci);
            }

            var min = int.MaxValue;
            for (var bit = 0; bit < (1 << D); bit++)
            {
                var restScore = G;
                var count = 0;
                for (var i = D - 1; i >= 0; i--)
                {
                    if ((bit & (1 << i)) != 0)
                    {
                        for (var j = 0; j < problems[i].Count; j++)
                        {
                            count++;
                            restScore -= problems[i].Score;
                            if (restScore <= 0)
                            {
                                min = Math.Min(count, min);
                                break;
                            }
                        }

                        restScore -= problems[i].CompleteBonus;
                        if (restScore <= 0)
                        {
                            min = Math.Min(count, min);
                            break;
                        }
                    }

                    if (restScore <= 0)
                    {
                        min = Math.Min(count, min);
                        break;
                    }
                }
            }

            Console.WriteLine(min);
        }

        readonly struct Problem
        {
            public Problem(int difficulty, int count, int completeBonus)
            {
                Difficulty = difficulty;
                Count = count;
                CompleteBonus = completeBonus;
                Score = Difficulty * 100;
            }

            public readonly int Score;

            public readonly int Difficulty;

            public readonly int Count;

            public readonly int CompleteBonus;
        }
    }
}
