#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); i++)
using namespace std;
using ll = long long;
using ld = long double;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(0);
    
    int N,X; cin >> N >> X;
    vector<ll> A(N), B(N);
    rep(i,N) cin >> A[i], A[i] -= X;
    rep(i,N) cin >> B[i];

    int MAX = 500 * 100;
    vector<vector<ll>> dp(MAX + MAX + 1, vector<ll>(2, +1e18));
    dp[MAX + 0][0] = 0;

    rep(i,N) {
        vector<vector<ll>> nt = dp;
        for(int s = 0; s <= MAX + MAX; s++) if(0 <= s + A[i] && s + A[i] <= MAX + MAX) {
            nt[s + A[i]][1] = min(nt[s + A[i]][1], dp[s][1] + B[i]);
            nt[s + A[i]][1] = min(nt[s + A[i]][1], dp[s][0] + B[i]);
        }
        swap(dp, nt);
    }

    ll ans = 1e18;
    for(int s = 0; s <= MAX; s++) ans = min(ans, dp[s + MAX][1]);
    cout << (ans == ll(1e18) ? -1 : ans) << endl;
}