using System;
using System.IO;
using System.Linq;
using System.Text;
using System.Diagnostics;
using System.Collections.Generic;
using System.Text.RegularExpressions;
using Enu = System.Linq.Enumerable;

class Program
{
    void Solve()
    {
        int N = reader.Int(), MaxCost = reader.Int(), NumE = reader.Int();
        int[] A = reader.IntLine().Select(x => x - 1).ToArray();
        int[] B = reader.IntLine().Select(x => x - 1).ToArray();
        int[] Cost = reader.IntLine();
        int[] Time = reader.IntLine();
        var dij = new Dijkstra(N);
        for (int i = 0; i < NumE; i++)
            dij.AddEdge(A[i], B[i], Cost[i], Time[i]);
        int ans = dij.MinCost(0, MaxCost);
        if (ans == Dijkstra.INF) ans = -1;
        Console.WriteLine(ans);
    }

    class Dijkstra
    {
        public static readonly int INF = (int)1e9;
        private readonly List<Edge>[] G;

        public Dijkstra(int V)
        {
            G = new List<Edge>[V];
            for (int i = 0; i < G.Length; i++) G[i] = new List<Edge>();
        }
        public void AddEdge(int from, int to, int cost, int time)
        {
            G[from].Add(new Edge(to, cost, time));
        }
        public int MinCost(int start, int MaxCost)
        {
            var minTime = new int[G.Length, MaxCost + 1];
            for (int i = 0; i < G.Length; i++)
                for (int c = 0; c <= MaxCost; c++)
                    minTime[i, c] = INF;
            minTime[start, 0] = 0;
            var heap = new Heap<Vertex>();
            heap.Push(new Vertex(start, 0, 0));

            while (heap.Count > 0)
            {
                var t = heap.Pop();
                int a = t.v;
                var cost = t.cost;
                int time = t.time;
                if (time > minTime[a, cost]) continue;

                foreach (var e in G[a])
                {
                    int b = e.to;
                    var nextCost = cost + e.cost;
                    int nextTime = time + e.time;
                    if (nextCost <= MaxCost && nextTime < minTime[b, nextCost])
                    {
                        minTime[b, nextCost] = nextTime;
                        heap.Push(new Vertex(b, nextCost, nextTime));
                    }
                }
            }
            return Enu.Range(0, MaxCost + 1).Min(c => minTime[G.Length - 1, c]);
        }

        public struct Vertex : IComparable<Vertex>
        {
            public int v, cost, time;
            public Vertex(int v, int cost, int time) { this.v = v; this.cost = cost; this.time = time; }
            public int CompareTo(Vertex other) { return Math.Sign(time - other.time); }
        }
        public struct Edge
        {
            public int to, cost, time;
            public Edge(int to, int cost, int time) { this.to = to; this.cost = cost; this.time = time; }
        }
    }


    class Heap<T>
    {
        public int Count { get { return size; } private set { size = value; } }
        private int size;
        private readonly int sign;
        private readonly List<T> A = new List<T>();
        private readonly Comparer<T> comp = Comparer<T>.Default;
        public Heap(bool greater = false)
        {
            sign = greater ? 1 : -1;
        }
        public T Peek() { return A[0]; }
        public void Push(T val)
        {
            if (size < A.Count) A[size] = val;
            else A.Add(val);
            Count++;
            int i = Count - 1;
            while (i > 0)
            {
                int parent = (i - 1) / 2;
                if (Math.Sign(comp.Compare(val, A[parent])) == sign)
                {
                    A[i] = A[parent];
                    i = parent;
                }
                else { break; }
            }
            A[i] = val;
        }
        public T Pop()
        {
            T res = A[0];
            T val = A[--Count];
            if (Count == 0) return res;
            int i = 0;
            while (i * 2 + 1 < Count)
            {
                int L = i * 2 + 1;
                int R = i * 2 + 2;
                if (R < Count && Math.Sign(comp.Compare(A[R], A[L])) == sign) { L = R; }
                if (Math.Sign(comp.Compare(A[L], val)) == sign) { A[i] = A[L]; i = L; }
                else { break; }
            }
            A[i] = val;
            return res;
        }
    }


    Reader reader = new Reader(Console.In);
    static void Main() { new Program().Solve(); }
}

class Reader
{
    private readonly TextReader reader;
    private readonly char[] separator = { ' ' };
    private readonly StringSplitOptions removeOp = StringSplitOptions.RemoveEmptyEntries;
    private string[] A = new string[0];
    private int i;

    public Reader(TextReader r) { reader = r; }
    public bool HasNext() { return Enqueue(); }
    public string String() { return Dequeue(); }
    public int Int() { return int.Parse(Dequeue()); }
    public long Long() { return long.Parse(Dequeue()); }
    public double Double() { return double.Parse(Dequeue()); }
    public int[] IntLine() { var s = Line(); return s == "" ? new int[0] : Array.ConvertAll(Split(s), int.Parse); }
    public int[] IntArray(int N) { return Enu.Range(0, N).Select(i => Int()).ToArray(); }
    public int[][] IntGrid(int H) { return Enu.Range(0, H).Select(i => IntLine()).ToArray(); }
    public string[] StringArray(int N) { return Enu.Range(0, N).Select(i => Line()).ToArray(); }
    public string Line() { return reader.ReadLine().Trim(); }
    private string[] Split(string s) { return s.Split(separator, removeOp); }
    private bool Enqueue()
    {
        if (i < A.Length) return true;
        string line = reader.ReadLine();
        if (line == null) return false;
        if (line == "") return Enqueue();
        A = Split(line);
        i = 0;
        return true;
    }
    private string Dequeue() { Enqueue(); return A[i++]; }
}