import std.algorithm, std.conv, std.range, std.stdio, std.string;

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

  auto yij = new int[][](n, n);
  auto mij = new int[][](n, n);
  foreach (i; v.iota) {
    yij[si[i]][ti[i]] = yi[i];
    mij[si[i]][ti[i]] = mi[i];
  }

  auto dp = new int[int][](n);
  dp[0][0] = 0;

  foreach (i; 0..n-1) {
    foreach (j; i+1..n) {
      auto y = yij[i][j], m = mij[i][j];
      if (y > 0 || m > 0) {
        foreach (k; dp[i].byKeyValue) {
          auto ny = k.key + y;
          auto nm = k.value + m;
          if (ny <= c) {
            if (ny in dp[j])
              dp[j][ny] = min(dp[j][ny], nm);
            else
              dp[j][ny] = nm;
          }
        }
      }
    }
  }

  auto ri = dp[n - 1].values;
  if (ri.empty)
    writeln(-1);
  else
    writeln(ri.reduce!min);
}