#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
using ll = long long;
const int INF = 0x3f3f3f3f;
const ll LINF = 0x3f3f3f3f3f3f3f3fLL;
const double EPS = 1e-8;
const int MOD = 1000000007;
// const int MOD = 998244353;
const int dy[] = {1, 0, -1, 0}, dx[] = {0, -1, 0, 1};
const int dy8[] = {1, 1, 0, -1, -1, -1, 0, 1}, dx8[] = {0, -1, -1, -1, 0, 1, 1, 1};
template <typename T, typename U> inline bool chmax(T &a, U b) { return a < b ? (a = b, true) : false; }
template <typename T, typename U> inline bool chmin(T &a, U b) { return a > b ? (a = b, true) : false; }
struct IOSetup {
  IOSetup() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(20);
  }
} iosetup;

int main() {
  const int M = 100 * 500;
  int n, x; cin >> n >> x;
  vector<int> a(n), b(n);
  REP(i, n) cin >> a[i], a[i] -= x;
  REP(i, n) cin >> b[i];
  vector dp(n + 1, vector(M * 2 + 1, INF));
  dp[0][M] = 0;
  REP(i, n) REP(j, M * 2 + 1) {
    if (0 <= j + a[i] && j + a[i] <= M * 2) chmin(dp[i + 1][j + a[i]], dp[i][j]);
    chmin(dp[i + 1][j], dp[i][j] + b[i]);
  }
  int ans = accumulate(ALL(b), 0);
  FOR(j, M, M * 2 + 1) chmin(ans, dp[n][j]);
  cout << (ans == accumulate(ALL(b), 0) ? -1 : ans) << '\n';
  return 0;
}