import java.io.IOException;
import java.util.InputMismatchException;
import java.util.LinkedList;
import java.util.List;
import java.util.PriorityQueue;

public class Main {
	int n;
	List<Edge>[] e;

	class Edge {
		int to;
		int cost, dist;

		Edge(int to, int cost, int dist) {
			this.to = to;
			this.cost = cost;
			this.dist = dist;
		}
	}

	class D implements Comparable<D> {
		int pos;
		int rem;
		int len;

		D(int pos, int rem, int len) {
			this.pos = pos;
			this.rem = rem;
			this.len = len;
		}

		@Override
		public int compareTo(D o) {
			if (this.len != o.len)
				return this.len - o.len;
			if (this.rem != o.rem)
				return this.rem - o.rem;
			return this.pos - o.pos;
		}

		@Override
		public String toString() {
			return "(" + pos + ", " + rem + ", " + len + ")";
		}
	}

	int dijkstra(int c) {
		PriorityQueue<D> queue = new PriorityQueue<D>();
		queue.add(new D(0, c, 0));

		while (!queue.isEmpty()) {
			D d = queue.poll();
			int pos = d.pos;
			int rem = d.rem;
			int len = d.len;

			if (pos == n - 1) {
				return len;
			}

			for (Edge e : e[pos]) {
				int npos = e.to;
				int nrem = rem - e.cost;
				int nlen = len + e.dist;
				if (nrem < 0)
					continue;
				queue.add(new D(npos, nrem, nlen));
			}
		}

		return -1;
	}

	void run() {
		MyScanner sc = new MyScanner();

		n = sc.nextInt();
		int c = sc.nextInt();
		int m = sc.nextInt();
		int[] u = sc.nextIntArray(m);
		int[] v = sc.nextIntArray(m);
		int[] y = sc.nextIntArray(m);
		int[] t = sc.nextIntArray(m);
		e = new LinkedList[n];
		for (int i = 0; i < n; i++) {
			e[i] = new LinkedList<Edge>();
		}
		for (int i = 0; i < m; i++) {
			int a = u[i] - 1;
			int b = v[i] - 1;
			e[a].add(new Edge(b, y[i], t[i]));
		}

		System.out.println(dijkstra(c));
	}

	public static void main(String[] args) {
		new Main().run();
	}

	public void mapDebug(int[][] a) {
		System.out.println("--------map display---------");
		for (int i = 0; i < a.length; i++) {
			for (int j = 0; j < a[i].length; j++) {
				System.out.printf("%3d ", a[i][j]);
			}
			System.out.println();
		}
		System.out.println("----------------------------" + '\n');
	}

	class MyScanner {
		int read() {
			try {
				return System.in.read();
			} catch (IOException e) {
				throw new InputMismatchException();
			}
		}

		boolean isSpaceChar(int c) {
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}

		boolean isEndline(int c) {
			return c == '\n' || c == '\r' || c == -1;
		}

		int nextInt() {
			return Integer.parseInt(next());
		}

		int[] nextIntArray(int n) {
			int[] array = new int[n];
			for (int i = 0; i < n; i++)
				array[i] = nextInt();
			return array;
		}

		long nextLong() {
			return Long.parseLong(next());
		}

		long[] nextLongArray(int n) {
			long[] array = new long[n];
			for (int i = 0; i < n; i++)
				array[i] = nextLong();
			return array;
		}

		double nextDouble() {
			return Double.parseDouble(next());
		}

		double[] nextDoubleArray(int n) {
			double[] array = new double[n];
			for (int i = 0; i < n; i++)
				array[i] = nextDouble();
			return array;
		}

		String next() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isSpaceChar(c));
			return res.toString();
		}

		String[] nextStringArray(int n) {
			String[] array = new String[n];
			for (int i = 0; i < n; i++)
				array[i] = next();

			return array;
		}

		String nextLine() {
			int c = read();
			while (isEndline(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isEndline(c));
			return res.toString();
		}
	}
}