import std.algorithm, std.array, std.container, std.range, std.bitmanip;
import std.numeric, std.math, std.bigint, std.random;
import std.string, std.conv, std.stdio, std.typecons;

struct path {
  int e;
  int y;
  int m;
}

void main()
{
  auto n = readln.chomp.to!int;
  auto c = readln.chomp.to!int;
  auto v = readln.chomp.to!int;
  auto si = readln.split.map!(to!int).map!("a - 1");
  auto ti = readln.split.map!(to!int).map!("a - 1");
  auto yi = readln.split.map!(to!int);
  auto mi = readln.split.map!(to!int);

  auto tij = new int[][](n);
  auto yij = new int[][](n);
  auto mij = new int[][](n);

  foreach (i; 0..v) {
    tij[si[i]] ~= ti[i];
    yij[si[i]] ~= yi[i];
    mij[si[i]] ~= mi[i];
  }

  auto min = int.max;

  auto stack = SList!path();
  stack.insertFront(path(0, 0, 0));
  while (!stack.empty) {
    auto p = stack.front;
    stack.removeFront;

    if (p.e == n - 1) {
      if (p.m < min) min = p.m;
      continue;
    }

    foreach (i, t; tij[p.e]) {
      auto y = yij[p.e][i];
      auto m = mij[p.e][i];
      if (y == 0 || m == 0 || p.m + m > min || p.y + y > c)
        continue;
      stack.insertFront(path(t, p.y + y, p.m + m));
    }
  }

  writeln(min == int.max ? -1 : min);
}