Problem: Demonstrative competitions will be held in the run-up to the 20NN Berlatov Olympic Games. Today is the day for the running competition!

Berlatov team consists of 2n runners which are placed on two running tracks; n runners are placed on each track. The runners are numbered from 1 to n on each track. The runner with number i runs through the entire track in i seconds.

The competition is held as follows: first runners on both tracks start running at the same time; when the slower of them arrives at the end of the track, second runners on both tracks start running, and everyone waits until the slower of them finishes running, and so on, until all n pairs run through the track.

The organizers want the run to be as long as possible, but if it lasts for more than k seconds, the crowd will get bored. As the coach of the team, you may choose any order in which the runners are arranged on each track (but you can't change the number of runners on each track or swap runners between different tracks).

You have to choose the order of runners on each track so that the duration of the competition is as long as possible, but does not exceed k seconds.

Formally, you want to find two permutations p and q (both consisting of n elements) such that sum = ∑_{i=1}^{n} max(p_i, q_i) is maximum possible, but does not exceed k. If there is no such pair, report about it.

Input

The first line contains two integers n and k (1 ≤ n ≤ 10^6, 1 ≤ k ≤ n^2) — the number of runners on each track and the maximum possible duration of the competition, respectively.

Output

If it is impossible to reorder the runners so that the duration of the competition does not exceed k seconds, print -1. 

Otherwise, print three lines. The first line should contain one integer sum — the maximum possible duration of the competition not exceeding k. The second line should contain a permutation of n integers p_1, p_2, ..., p_n (1 ≤ p_i ≤ n, all p_i should be pairwise distinct) — the numbers of runners on the first track in the order they participate in the competition. The third line should contain a permutation of n integers q_1, q_2, ..., q_n (1 ≤ q_i ≤ n, all q_i should be pairwise distinct) — the numbers of runners on the second track in the order they participate in the competition. The value of sum = ∑_{i=1}^{n} max(p_i, q_i) should be maximum possible, but should not exceed k. If there are multiple answers, print any of them.

Examples

Input


5 20


Output


20
1 2 3 4 5 
5 2 4 3 1 


Input


3 9


Output


8
1 2 3 
3 2 1 


Input


10 54


Output


-1

Note

In the first example the order of runners on the first track should be [5, 3, 2, 1, 4], and the order of runners on the second track should be [1, 4, 2, 5, 3]. Then the duration of the competition is max(5, 1) + max(3, 4) + max(2, 2) + max(1, 5) + max(4, 3) = 5 + 4 + 2 + 5 + 4 = 20, so it is equal to the maximum allowed duration.

In the first example the order of runners on the first track should be [2, 3, 1], and the order of runners on the second track should be [2, 1, 3]. Then the duration of the competition is 8, and it is the maximum possible duration for n = 3.

Solution (in JAVA):

Solution:
import java.io.*;
import java.util.*;

import static java.lang.Math.*;
import static java.util.Arrays.*;

public class Main {
    public static void main(String[] args) throws IOException {
        FastScanner in = new FastScanner(System.in);
        PrintWriter out = new PrintWriter(System.out);
        int n = in.nextInt();
        int ans[] = new int[n];
        long k = in.nextLong();
        for (int i = 0; i < n; i++) {
            ans[i] = i + 1;
        }
        int l = 0;
        int r = n - 1;
        long s = ((long)n * (n + 1)) >> 1;
        if(k < s){
            out.println(-1);
            out.close();
            return;
        }
        while (l < r){
            if(r - l + s <= k){
                int t = ans[l];
                ans[l] = ans[r];
                ans[r] = t;
                s+=r - l;
                r--;
            }
            l++;
        }
        out.println(s);
        for (int i = 0; i < n; i++) {
            out.print(i+1 + " ");
        }
        out.println();
        for (int i = 0; i < n; i++) {
           out.print(ans[i] + " ");
        }
        out.close();
    }
}

class RANDOMIZER {
    static Random rnd = new Random();

    static int randomize() {
        return rnd.nextInt();
    }
}

class array {
    long a[];

    array(long a[]) {
        this.a = a;
    }

    array(int n) {
        a = new long[n];
    }

    void shuffle() {
        for (int i = 0; i < a.length; i++) {
            int id1 = ((RANDOMIZER.randomize() % a.length) + a.length) % a.length;
            int id2 = ((RANDOMIZER.randomize() % a.length) + a.length) % a.length;
            long t = a[id1];
            a[id1] = a[id2];
            a[id2] = t;
        }
    }

    void reverse(int l, int r) {
        for (int i = l; i < l + (r - l + 1) >> 1; i++) {
            long t = a[i];
            a[i] = a[r - i];
            a[r - i] = t;
        }
    }

    long[] right_shift(int shift) {
        long aa[] = new long[a.length];
        for (int i = 0; i < a.length; i++) {
            aa[(i + shift) % a.length] = a[i];
        }
        return aa;
    }

    void add(int l, int r, long val) {
        for (int i = l; i <= r; i++) {
            a[i] += val;
        }
    }

    void print(PrintWriter out) {
        for (int i = 0; i < a.length; i++) {
            out.print(a[i] + " ");
        }
    }

    void copy(long t[]) {
        for (int i = 0; i < a.length; i++) {
            a[i] = t[i];
        }
    }

    void scan(FastScanner in) throws IOException {
        for (int i = 0; i < a.length; i++) {
            a[i] = in.nextLong();
        }
    }

    long getSum() {
        long sum = 0;
        long md = (long) 1e16;
        for (int i = 0; i < a.length; i++) {
            sum += a[i];
            sum %= md;
        }
        return sum;
    }

    long getMin() {
        long min = Long.MAX_VALUE;
        for (int i = 0; i < a.length; i++) {
            min = min(min, a[i]);
        }
        return min;
    }

    long getMax() {
        long max = Long.MIN_VALUE;
        for (int i = 0; i < a.length; i++) {
            max = max(max, a[i]);
        }
        return max;
    }

    int ceilingID(long val) {
        int l = 0;
        int r = a.length - 1;
        while (l + 1 != r) {
            int m = (l + r) >> 1;
            if (a[m] >= val) r = m;
            else l = m;
        }
        int pr = l;
        if (pr > 0 && a[pr - 1] >= val) pr--;
        if (a[pr] < val) pr++;
        if (pr < a.length && a[pr] < val) pr++;
        return pr;
    }
}

class dsu {
    int p[];
    int max[];

    dsu(int n) {
        p = new int[n];
        max = new int[n];
        for (int i = 0; i < n; i++) {
            p[i] = i;
            max[i] = i;
        }
    }

    int get(int a) {
        if (p[a] == a) return a;
        return p[a] = get(p[a]);
    }

    void merge(int a, int b) {
        a = get(a);
        b = get(b);
        if (a != b) {
            p[a] = b;
            max[b] = max(max[a], max[b]);
        }
    }
}

class vertex {
    int next[];
}

class trie {
    vertex t[];
    int sz = 1;
    int k;

    trie(int k) {
        this.k = k;
        t = new vertex[300000];
        for (int i = 0; i < t.length; i++) {
            t[i] = new vertex();
            t[i].next = new int[k];
            for (int j = 0; j < k; j++) {
                t[i].next[j] = -1;
            }
        }
    }

    void add(String s, int id) {
        int v = 0;
        for (int i = 0; i < s.length(); i++) {
            char rc = (char) (s.charAt(i) - 'a');
            if (t[v].next[rc] == -1) {
                t[v].next[rc] = sz++;
            }
            v = t[v].next[rc];
        }
    }
}

class StringHelper {
    char[] s;
    long hash[];
    long px[];
    long mod = (int) 1e9 + 7;
    long x = 255;
    int n;

    public StringHelper(String s) {
        this.s = s.toCharArray();
        n = s.length();
    }

    int[] pi() {
        int pi[] = new int[n];
        for (int i = 1; i < n; i++) {
            int j = pi[i - 1];
            while (j > 0 && s[i] != s[j]) j = pi[j - 1];
            pi[i] = s[i] == s[j] ? j + 1 : j;
        }
        return pi;
    }

    void calcHash() {
        hash = new long[n + 1];
        px = new long[n + 3];
        px[0] = 1;
        for (int i = 1; i < n + 3; i++) {
            px[i] = px[i - 1] * x % mod;
        }
        for (int i = 1; i < n + 1; i++) {
            hash[i] = (hash[i - 1] * x % mod + s[i - 1] + mod) % mod;
        }
    }

    long getHash(int l, int r) {
        return (hash[r + 1] - hash[l] * px[r - l + 1] % mod + mod) % mod;
    }
}

class IMPLICITDT {
    long val;
    int y;
    int sz;
    IMPLICITDT l, r;

    static int getSize(IMPLICITDT t) {
        return t == null ? 0 : t.sz;
    }

    private static void recalc(IMPLICITDT t) {
        if (t == null) return;
        int LSZ = t.l == null ? 0 : t.l.sz;
        int RSZ = t.r == null ? 0 : t.r.sz;
        t.sz = LSZ + RSZ + 1;
    }

    IMPLICITDT() {
    }

    IMPLICITDT(long cost, int y, IMPLICITDT l, IMPLICITDT r) {
        this.val = cost;
        this.y = y;
        this.l = l;
        this.r = r;
        recalc(this);
    }

    IMPLICITDT(long cost, int y) {
        this.val = cost;
        this.y = y;
        recalc(this);
    }

    static long get(IMPLICITDT t, int id) {
        int LSZ = getSize(t.l);
        if (LSZ == id) return t.val;
        if (LSZ < id) return get(t.r, id - LSZ - 1);
        return get(t.l, id);
    }

    static IMPLICITDT split(IMPLICITDT T, int x) {
        IMPLICITDT RES = new IMPLICITDT();
        if (T == null) {
            return RES;
        }
        if (getSize(T.l) > x) {
            IMPLICITDT lsplit = split(T.l, x);
            RES.l = lsplit.l;
            RES.r = T;
            T.l = lsplit.r;
        } else {
            IMPLICITDT rsplit = split(T.r, x - getSize(T.l) - 1);
            RES.r = rsplit.r;
            RES.l = T;
            T.r = rsplit.l;
        }
        recalc(RES);
        recalc(T);
        return RES;
    }

    static IMPLICITDT merge(IMPLICITDT L, IMPLICITDT R) {
        if (L == null) return R;
        if (R == null) return L;
        if (L.y > R.y) return new IMPLICITDT(L.val, L.y, L.l, merge(L.r, R));
        else return new IMPLICITDT(R.val, R.y, merge(L, R.l), R.r);
    }

    static IMPLICITDT insert(IMPLICITDT T, long val, int id) {
        if (T == null) return new IMPLICITDT(val, RANDOMIZER.randomize());
        IMPLICITDT _T = split(T, id);
        IMPLICITDT _TR = new IMPLICITDT(val, RANDOMIZER.randomize());
        IMPLICITDT NEWTREAP = merge(_T.l, _TR);
        IMPLICITDT TREAP = merge(NEWTREAP, _T.r);
        recalc(TREAP);
        return TREAP;
    }
}

class stSUM {
    int t[];
    int a[];

    stSUM(int a[]) {
        this.a = a;
        t = new int[a.length * 4];
    }

    void build(int v, int l, int r) {
        if (l == r) t[v] = a[l];
        else {
            int m = (l + r) >> 1;
            build(v * 2, l, m);
            build(v * 2 + 1, m + 1, r);
            t[v] = t[v * 2] + t[v * 2 + 1];
        }
    }

    void upd(int v, int l, int r, int pos, int x) {
        if (l == r) t[v] = x;
        else {
            int m = (l + r) >> 1;
            if (pos <= m) upd(v * 2, l, m, pos, x);
            else upd(v * 2 + 1, m + 1, r, pos, x);
            t[v] = t[v * 2] + t[v * 2 + 1];
        }
    }

    int query(int v, int l, int r, int ql, int qr) {
        if (ql <= l && r <= qr) return t[v];
        if (l > qr || ql > r) return 0;
        int m = (l + r) >> 1;
        return query(v * 2, l, m, ql, qr) + query(v * 2 + 1, m + 1, r, ql, qr);
    }
}

class stMIN {
    int t[];
    int a[];

    stMIN(int a[]) {
        this.a = a;
        t = new int[a.length * 4];
    }

    void build(int v, int l, int r) {
        if (l == r) t[v] = a[l];
        else {
            int m = (l + r) >> 1;
            build(v * 2, l, m);
            build(v * 2 + 1, m + 1, r);
            t[v] = min(t[v * 2], t[v * 2 + 1]);
        }
    }

    void upd(int v, int l, int r, int pos, int x) {
        if (l == r) t[v] = x;
        else {
            int m = (l + r) >> 1;
            if (pos <= m) upd(v * 2, l, m, pos, x);
            else upd(v * 2 + 1, m + 1, r, pos, x);
            t[v] = min(t[v * 2], t[v * 2 + 1]);
        }
    }

    int query(int v, int l, int r, int ql, int qr) {
        if (ql <= l && r <= qr) return t[v];
        if (l > qr || ql > r) return Integer.MAX_VALUE;
        int m = (l + r) >> 1;
        return min(query(v * 2, l, m, ql, qr), query(v * 2 + 1, m + 1, r, ql, qr));
    }
}

class DT {
    long val;
    int x, y;
    int sz;
    DT l, r;

    DT() {
        recalc(this);
    }

    DT(int x, int y, long val) {
        this.x = x;
        this.y = y;
        this.val = val;
        recalc(this);
    }

    DT(int x, int y, DT l, DT r, long val) {
        this.x = x;
        this.y = y;
        this.l = l;
        this.r = r;
        this.val = val;
        recalc(this);
    }

    static DT split(DT t, int x) {
        DT res = new DT();
        if (t == null) {
            res.l = null;
            res.r = null;
            return res;
        }
        if (x < t.x) {
            DT lsplit = split(t.l, x);
            res.l = lsplit.l;
            res.r = t;
            t.l = lsplit.r;
        } else {
            DT rsplit = split(t.r, x);
            res.r = rsplit.r;
            res.l = t;
            t.r = rsplit.l;
        }
        recalc(t);
        recalc(res);
        return res;
    }

    static DT merge(DT t1, DT t2) {
        if (t1 == null || t2 == null)
            return t1 == null ? t2 : t1;
        if (t1.y < t2.y) {
            t1.r = merge(t1.r, t2);
            recalc(t1);
            return t1;
        } else {
            t2.l = merge(t1, t2.l);
            recalc(t2);
            return t2;
        }
    }

    static void recalc(DT t) {
        if (t == null) return;
        int lsz = t.l == null ? 0 : t.l.sz;
        int rsz = t.r == null ? 0 : t.r.sz;
        t.sz = lsz + rsz + 1;
    }

    static DT insert(DT t, int x, long val) {
        try {
            if (t == null) {
                DT ret = new DT(x, RANDOMIZER.randomize(), val);
                recalc(ret);
                return ret;
            }
            DT split = split(t, x);
            DT prelast = merge(split.l, new DT(x, RANDOMIZER.randomize(), val));
            DT newtreap = merge(prelast, split.r);
            recalc(newtreap);
            return newtreap;
        } catch (Exception e) {
            System.exit(0);
            return new DT();
        }
    }

    static long find_kth(DT t, int k) {
        if (t.l == null && k == 1)
            return t.val;
        if (t.l != null && t.l.sz == k - 1)
            return t.val;
        if (t.l != null && t.l.sz >= k)
            return find_kth(t.l, k);
        else
            return find_kth(t.r, k - (t.l == null ? 0 : t.l.sz) - 1);
    }

}


class FT {
    private int[] a;
    private long[] t;

    FT(int[] a) {
        this.a = a;
        t = new long[a.length];
    }

    void inc(int i, int delta) {
        for (; i < a.length; i = (i | (i + 1)))
            t[i] += delta;
    }

    long sum(int l, int r) {
        return sum(r) - sum(l - 1);
    }

    private long sum(int r) {
        long sum = 0;
        for (; r >= 0; r = (r & (r + 1)) - 1) {
            sum += t[r];
        }
        return sum;
    }
}

class LAZY_ST {
    long min[], sum[], set[];
    int last;
    long not_set = Long.MAX_VALUE;

    LAZY_ST(long a[]) {
        int n = a.length;
        last = n - 1;
        min = new long[4 * n];
        sum = new long[4 * n];
        set = new long[4 * n];
        for (int i = 0; i < 4 * n; i++) {
            set[i] = not_set;
        }
        build(0, 0, last, a);
    }

    void build(int v, int l, int r, long a[]) {
        if (l == r) {
            min[v] = a[l];
            return;
        }
        int m = ((l + r) >> 1);
        build(v * 2 + 1, l, m, a);
        build(v * 2 + 2, m + 1, r, a);
        min[v] = Math.min(min[v * 2 + 1], min[v * 2 + 2]);
    }

    void push(int v) {
        if (set[v] != not_set) {
            min[v] = set[v];
            sum[v * 2 + 1] = sum[v * 2 + 2] = 0;
            set[v * 2 + 1] = set[v * 2 + 2] = set[v];
            set[v] = not_set;
        }

        min[v] += sum[v];
        sum[v * 2 + 1] += sum[v];
        sum[v * 2 + 2] += sum[v];
        sum[v] = 0;
    }

    void upd(int v) {
        min[v] = Math.min(get_el(v * 2 + 1), get_el(v * 2 + 2));
    }

    long get_el(int v) {
        return (set[v] == not_set ? min[v] : set[v]) + sum[v];
    }

    void set(int l, int r, long x) {
        set(0, 0, last, l, r, x);
    }

    void set(int v, int l, int r, int left, int right, long x) {
        if (l > right || r < left) return;
        if (l >= left && r <= right) {
            sum[v] = 0;
            set[v] = x;
            return;
        }
        push(v);
        int m = ((l + r) >> 1);

        set(v * 2 + 1, l, m, left, right, x);
        set(v * 2 + 2, m + 1, r, left, right, x);

        upd(v);
    }

    void add(int l, int r, long x) {
        add(0, 0, last, l, r, x);
    }

    void add(int v, int l, int r, int left, int right, long x) {
        if (l > right || r < left) return;
        if (l >= left && r <= right) {
            sum[v] += x;
            return;
        }
        push(v);
        int m = ((l + r) >> 1);

        add(v * 2 + 1, l, m, left, right, x);
        add(v * 2 + 2, m + 1, r, left, right, x);

        upd(v);
    }

    long get(int l, int r) {
        return get(0, 0, last, l, r);
    }

    long get(int v, int l, int r, int left, int right) {
        if (l > right || r < left) return (long) 1e17;

        if (l >= left && r <= right) {
            return get_el(v);
        }
        push(v);
        int m = ((l + r) >> 1);

        long ans = Math.min(get(v * 2 + 1, l, m, left, right), get(v * 2 + 2, m + 1, r, left, right));
        upd(v);
        return ans;
    }

}

class multiset {
    TreeMap<Long, Integer> t;

    void insert(long val) {
        t.put(val, t.getOrDefault(val, 0) + 1);
    }

    void erase(long val) {
        int nw = t.getOrDefault(val, 1);
        if (nw == 1) t.remove(val);
        else t.put(val, nw - 1);
    }

    long ceiling(long val) {
        return t.ceilingKey(val);
    }

    long floor(long val) {
        return t.floorKey(val);
    }

    long higher(long val) {
        return t.higherKey(val);
    }

    long lower(long val) {
        return t.lowerKey(val);
    }

    int count(long val) {
        return t.getOrDefault(val, 0);
    }
}

class FastScanner {
    BufferedReader br;
    StringTokenizer st;

    FastScanner(File f) throws FileNotFoundException {
        br = new BufferedReader(new FileReader(f));
    }

    FastScanner(InputStream is) {
        br = new BufferedReader(new InputStreamReader(is));
    }

    String next() throws IOException {
        while (st == null || !st.hasMoreTokens())
            st = new StringTokenizer(br.readLine());
        return st.nextToken();
    }

    int nextInt() throws IOException {
        return Integer.parseInt(next());
    }

    long nextLong() throws IOException {
        return Long.parseLong(next());
    }
}