#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
#include <fstream>
#include <utility>
#include <functional>
#include <time.h>
#include <stack>
#include <array>
#define popcount __builtin_popcount
using namespace std;
typedef long long int ll;
typedef pair<int, int> P;

int main()
{
	int n, x; cin>>n>>x;
	int a[505], b[505];
	const int geta=100;
	for(int i=0; i<n; i++){
		cin>>a[i];
		a[i]-=x;
		a[i]+=geta;
	}
	int s=0;
	for(int i=0; i<n; i++){
	    cin>>b[i];
	    s+=b[i];
	}
	int dp[501][200*500+1];
	const int INF=1e9+7;
	for(int i=0; i<=n; i++) for(int j=0; j<=2*geta*n; j++) dp[i][j]=INF;
	dp[0][0]=0;
	for(int i=0; i<n; i++){
		for(int j=0; j<=2*geta*i; j++){
			dp[i+1][j+a[i]]=min(dp[i+1][j+a[i]], dp[i][j]);
			dp[i+1][j+geta]=min(dp[i+1][j+geta], dp[i][j]+b[i]);
		}
	}
	int ans=s;
	for(int i=geta*n; i<=2*geta*n; i++) ans=min(ans, dp[n][i]);
	if(ans<s) cout<<ans<<endl;
	else cout<<-1<<endl;
	return 0;
}