#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll=int;
using ld=long double;
ld pie=3.141592653589793;
ll inf=1444999994;
ll mod=1000000007;
int main(){
    ll n,x;
    cin >>  n >> x;
    vector<ll>a(n),b(n);
    ll sum=0;
    for (ll i = 0; i < n; i++)
    {
        cin >> a[i];
        a[i]-=x;
    }
    for (ll i = 0; i < n; i++)
    {
        cin >> b[i];
    }
    vector<ll>c,d;
    for (ll i = 0; i < n; i++)
    {
        if (a[i]<0)
        {
            c.push_back(-a[i]);
            d.push_back(b[i]);
        }else{
            sum+=a[i];
        }
    }
    n=c.size();
    if (n==0)
    {
        cout << 0 << endl;
        return 0;
    }
    if (n==a.size())
    {
        cout << -1 << endl;
        return 0;
    }
    vector<vector<ll>>dp(n,vector<ll>(sum+1,inf));
    dp[0][0]=d[0];
    if (c[0]<=sum)
    {
        dp[0][c[0]]=0;
    }
    for (ll i = 1; i < n; i++)
    {
        for (ll j = 0; j <=sum; j++)
        {
            if (dp[i-1][j]==inf)
            {
                continue;
            }
            dp[i][j]=min(dp[i][j],dp[i-1][j]+d[i]);
            if (j+c[i]<=sum)
            {
                dp[i][j+c[i]]=min(dp[i][j+c[i]],dp[i-1][j]);
            }
        }
    }
    ll ans=inf;
    for (ll i = 0; i <=sum; i++)
    {
        ans=min(ans,dp[n-1][i]);
    }
    if (ans==inf)
    {
        cout << -1 << endl;
    }else{
        cout << ans << endl;
    }
    
}