using System;
using System.Linq;

namespace No1{
    public class Program{
        public static void Main(string[] args){
            var sr = new StreamReader();
            //---------------------------------
            var N = sr.Next<int>();//街の数
            var C = sr.Next<int>();//手持ちのお金
            var V = sr.Next<int>();//道の数
            var Rv = sr.Next<int>(4, V).Transpose()
                .Select(a => new {from = a[0], to = a[1], cost = a[2], time = a[3]}).OrderBy(a => a.to);

            var dp = new int[N + 1, C + 1].ToJaggedArray();
            dp[1][0] = 1;

            foreach(var r in Rv){
                for(var i = r.cost; i <= C; i++){
                    if(dp[r.from][i - r.cost] != 0) {
                        if(dp[r.to][i] == 0 || dp[r.to][i] > dp[r.from][i - r.cost] + r.time){
                            dp[r.to][i] = dp[r.from][i - r.cost] + r.time;
                        }
                    }
                }
            }

            Console.WriteLine(dp[N].Where(x => x != 0).DefaultIfEmpty(0).Min() - 1);
            //---------------------------------
        }
    }

    public static class ExMethod{
        public static T[][] Transpose<T>(this T[][] src){
            var x = src.Length;
            var y = src[0].Length;

            var ret = new T[y][];
            for(var i = 0; i < y; i++){
                ret[i] = new T[x];
                for(var j = 0; j < x; j++){
                    ret[i][j] = src[j][i];
                }
            }

            return ret;
        }

        public static T[][] ToJaggedArray<T>(this T[,] src){
            var x = src.GetLength(1);
            var y = src.GetLength(0);
            var ret = new T[y][];

            for(var i = 0; i < y; i++){
                ret[i] = new T[x];
                for(var j = 0; j < x; j++){
                    ret[i][j] = src[i, j];
                }
            }

            return ret;
        }
    }

    public class StreamReader{
        private readonly char[] _c = {' '};
        private int _index = -1;
        private string[] _input = new string[0];

        public T Next<T>(){
            if(_index == _input.Length - 1){
                _index = -1;
                while(true){
                    string rl = Console.ReadLine();
                    if(rl == null){
                        if(typeof(T).IsClass) return default(T);
                        return (T)typeof(T).GetField("MinValue").GetValue(null);
                    }
                    if(rl != ""){
                        _input = rl.Split(_c, StringSplitOptions.RemoveEmptyEntries);
                        break;
                    }
                }
            }
            return (T)Convert.ChangeType(_input[++_index], typeof(T), System.Globalization.CultureInfo.InvariantCulture);
        }

        public T[] Next<T>(int x){
            var ret = new T[x];
            for(var i = 0; i < x; ++i) ret[i] = Next<T>();
            return ret;
        }

        public T[][] Next<T>(int y, int x){
            var ret = new T[y][];
            for(var i = 0; i < y; ++i) ret[i] = Next<T>(x);
            return ret;
        }
    }
}