#include<iostream>
#include<vector>
#include<algorithm>
#define ll long long
using namespace std;
struct Stick{
    ll h;  // height
    ll p;  // penalty
    int in; // index
}stick[1000005];

bool cmp(Stick a, Stick b){
    return a.h <= b.h;
}

ll n, b, br1 = 1, br4 = 1, br5 = 1;
vector<int> A[1000005];

int main(){
    freopen("sticks.in", "r", stdin);
    freopen("sticks.out", "w", stdout);
    cin >> n >> b;
    ll br3 = n;
    for(int i = 1; i <= n; i++){
        cin >> stick[i].h;
        stick[i].in = i;
    }
    for(int i = 1; i <= n; i++) cin >> stick[i].p;

    sort(stick + 1, stick + n + 1, cmp);

    while(br1 <= n){
        ll br = 0;
        for(int i = br4; i <= n; i++){
            if(b > br && br1 <= n){
                if(br + stick[i].h <= b){
                    A[br5].push_back(stick[i].in);
                    br += stick[i].h;
                    br1++;
                    br4++;
                }
                else{
                    A[br5].push_back(stick[br3].in);
                    br += stick[br3].h;
                    br1++;
                    br3--;
                }
            }
            else{
                break;
            }
        }
        br5++;
    }
    
    cout << br5 - 1 << endl;
    for(int i = 1; i < br5; i++){
       cout << A[i].size() << " ";
        for(int j = 0; j < A[i].size(); j++){
            cout << A[i][j] << " ";
        }
        cout << endl;
    }
    return 0;
}