#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);
#define int ll
    int N,X; cin >> N >> X;
    vector<int> A(N), B(N);
    int BASE = 100;
    rep(i,N) cin >> A[i], A[i] -= X, A[i] += BASE;
    rep(i,N) cin >> B[i];
    int BSUM = accumulate(B.begin(), B.end(), 0);

    int MAX = 200 * 500;
    vector<int> dp(MAX + 1, 1e9);
    dp[0] = 0;
    rep(i,N) {
        vector<int> nt = dp;
        for(int s = 0; s <= MAX; s++) {
            if(s + A[i] <= MAX)
                nt[s + A[i]] = min(nt[s + A[i]], dp[s]);
            if(s + BASE <= MAX)
                nt[s + BASE] = min(nt[s + BASE], dp[s] + B[i]);
        }
        swap(nt, dp);
    }

    int ans = 1e9;
    for(int s = BASE * N; s <= MAX; s++) ans = min(ans, dp[s]);
    cout << (ans == ll(1e18) ? -1 : ans) << endl;
}