#include <bits/stdc++.h>
using namespace std;

int binarySearch(vector<int> &pref,int n,int left){
    int start =0;
    int end = n-1;
    int ans = -1;

    while(start<=end){
        int mid = (start+end)/2;
        if(pref[mid]>=left){
            ans = mid;
            end = mid-1;
        }
        else{
            start = mid+1;
        }
    }
    return ans;
}

int minimumPriorityQuotient(int N,int L,vector<int> &P,vector<int> &PQ){

    int sum =0;
    for(int i=0;i<N;i++){
        sum+=P[i];
    }

    if(sum<L){
        return -1;
    }

    vector<int> not_rare;
    vector<int> rare;

    for(int i=0;i<N;i++){

        if(PQ[i]==1){
            not_rare.push_back(P[i]);
        }
        else{
            rare.push_back(P[i]);
        }
    }

    sort(not_rare.begin(),not_rare.end(),greater<int>());
    sort(rare.begin(),rare.end(),greater<int>());

    vector<int> pref(rare.size()+1);

    for(int i=0;i<pref.size()-1;i++){
        pref[i+1] = pref[i] + rare[i];
    }

    int ans = 100000;

    int pos = binarySearch(pref,pref.size(),L);
    if(pos!=-1){
        ans = min(ans,2*pos);
    }

    int totalMem = 0;

    for(int i=0;i<not_rare.size();i++){
        int temp = i+1;
        totalMem+=not_rare[i];
        int left = L-totalMem;
        if(left){
            pos = binarySearch(pref,pref.size(),left);
            if(pos==-1){
                continue;
            }
            temp+=(2*pos);
        }
        ans = min(ans,temp);
    }
    return ans;
}

signed main() {

    int N;
    int L;
    cin>>N>>L;
    vector<int> P(N);
    vector<int> PQ(N);

    for(int i=0;i<N;i++)cin>>P[i];
    for(int i=0;i<N;i++)cin>>PQ[i];
    cout<<minimumPriorityQuotient(N,L,P,PQ)<<endl;

}