Problem: Long story short, shashlik is Miroslav's favorite food. Shashlik is prepared on several skewers simultaneously. There are two states for each skewer: initial and turned over.

This time Miroslav laid out n skewers parallel to each other, and enumerated them with consecutive integers from 1 to n in order from left to right. For better cooking, he puts them quite close to each other, so when he turns skewer number i, it leads to turning k closest skewers from each side of the skewer i, that is, skewers number i - k, i - k + 1, ..., i - 1, i + 1, ..., i + k - 1, i + k (if they exist). 

For example, let n = 6 and k = 1. When Miroslav turns skewer number 3, then skewers with numbers 2, 3, and 4 will come up turned over. If after that he turns skewer number 1, then skewers number 1, 3, and 4 will be turned over, while skewer number 2 will be in the initial position (because it is turned again).

As we said before, the art of cooking requires perfect timing, so Miroslav wants to turn over all n skewers with the minimal possible number of actions. For example, for the above example n = 6 and k = 1, two turnings are sufficient: he can turn over skewers number 2 and 5.

Help Miroslav turn over all n skewers.

Input

The first line contains two integers n and k (1 ≤ n ≤ 1000, 0 ≤ k ≤ 1000) — the number of skewers and the number of skewers from each side that are turned in one step.

Output

The first line should contain integer l — the minimum number of actions needed by Miroslav to turn over all n skewers. After than print l integers from 1 to n denoting the number of the skewer that is to be turned over at the corresponding step.

Examples

Input

7 2


Output

2
1 6 


Input

5 1


Output

2
1 4 

Note

In the first example the first operation turns over skewers 1, 2 and 3, the second operation turns over skewers 4, 5, 6 and 7.

In the second example it is also correct to turn over skewers 2 and 5, but turning skewers 2 and 4, or 1 and 5 are incorrect solutions because the skewer 3 is in the initial state after these operations.

Solution (in JAVA):

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

public class Stack2 {

    static class Reader {
        final private int BUFFER_SIZE = 1 << 16;
        private DataInputStream din;
        private byte[] buffer;
        private int bufferPointer, bytesRead;

        public Reader() {
            din = new DataInputStream(System.in);
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }

        public Reader(String file_name) throws IOException {
            din = new DataInputStream(new FileInputStream(file_name));
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }

        public String readLine() throws IOException {
            byte[] buf = new byte[64]; // line length
            int cnt = 0, c;
            while ((c = read()) != -1) {
                if (c == '\n')
                    break;
                buf[cnt++] = (byte) c;
            }
            return new String(buf, 0, cnt);
        }

        public int nextInt() throws IOException {
            int ret = 0;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();
            do {
                ret = ret * 10 + c - '0';
            } while ((c = read()) >= '0' && c <= '9');
            if (neg)
                return -ret;
            return ret;
        }

        public long nextLong() throws IOException {
            long ret = 0;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();
            do {
                ret = ret * 10 + c - '0';
            }
            while ((c = read()) >= '0' && c <= '9');
            if (neg)
                return -ret;
            return ret;
        }

        public double nextDouble() throws IOException {
            double ret = 0, div = 1;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();
            do {
                ret = ret * 10 + c - '0';
            }
            while ((c = read()) >= '0' && c <= '9');
            if (c == '.') {
                while ((c = read()) >= '0' && c <= '9') {
                    ret += (c - '0') / (div *= 10);
                }
            }
            if (neg)
                return -ret;
            return ret;
        }

        private void fillBuffer() throws IOException {
            bytesRead = din.read(buffer, bufferPointer = 0, BUFFER_SIZE);
            if (bytesRead == -1)
                buffer[0] = -1;
        }

        private byte read() throws IOException {
            if (bufferPointer == bytesRead)
                fillBuffer();
            return buffer[bufferPointer++];
        }

        public void close() throws IOException {
            if (din == null)
                return;
            din.close();
        }
    }

    static Reader sc = new Reader();
    static BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

    public static void main(String[] args) throws IOException {
        /*
         * For integer input: int n=inputInt();
         * For long input: long n=inputLong();
         * For double input: double n=inputDouble();
         * For String input: String s=inputString();
         * Logic goes here
         * For printing without space: print(a+""); where a is a variable of any datatype
         * For printing with space: printSp(a+""); where a is a variable of any datatype
         * For printing with new line: println(a+""); where a is a variable of any datatype
         */
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int k = sc.nextInt();
       // if(n%2!=0&&k%2==0 || (n%2==0&&k%2!=0)){
            List<Integer> list=new ArrayList<>();
            list.add(1);
            for(int i=1+2*k+1;i<=n;i+=2*k+1){
                list.add(i);
            }
           /* System.out.println(list.size());
            for(Integer integer:list){
                System.out.println(integer);
            }*/
       // }else {
            List<Integer> list1=new ArrayList<>();
            list1.add(k+1);
            for(int i=k+1+2*k+1;i<=n;i+=2*k+1){
                list1.add(i);
            }
            if(list.get(list.size()-1)+k>=n && list1.get(list1.size()-1)+k>=n){
                if(list.size()<=list1.size()){
                    System.out.println(list.size());
                    for(Integer integer:list){
                        System.out.println(integer);
                    }
                }else {
                    System.out.println(list1.size());
                    for(Integer integer:list1){
                        System.out.println(integer);
                    }
                }
            }else if(list.get(list.size()-1)+k>=n){
                System.out.println(list.size());
                for(Integer integer:list){
                    System.out.println(integer);
                }
            }else {
                System.out.println(list1.size());
                for(Integer integer:list1){
                    System.out.println(integer);
                }
            }
           /* System.out.println(list1.size());
            for(Integer integer:list1){
                System.out.println(integer);
            }*/



        bw.flush();
        bw.close();


    }

    public static int query(int l, int r, Scanner sc) {
        System.out.println("? " + l + " " + r);
        return sc.nextInt();

    }

    public static int getAns(int n) {
        if (n >= 1 && n <= 9) {
            return n;
        } else {
            int f = n;
            int c = 0;
            int d = 0;
            while (f != 0) {
                c++;
                d = f % 10;
                f /= 10;

            }
            // int y= (int) (n/(Math.pow(10,c-1)));
            StringBuilder stringBuilder = new StringBuilder();
            for (int j = 1; j <= c; j++) {
                stringBuilder.append(d);
            }
            int ynum = Integer.parseInt(stringBuilder.toString());
            if (n >= ynum) {
                return 1 + getAns(ynum - 1);
            } else {
                if (d == 1) {
                    StringBuilder stringBuilder1 = new StringBuilder();
                    for (int j = 1; j <= c - 1; j++) {
                        stringBuilder1.append(9);
                    }
                    int ynum1 = Integer.parseInt(stringBuilder1.toString());
                    return getAns(ynum1);
                } else {
                    StringBuilder stringBuilder1 = new StringBuilder();
                    for (int j = 1; j <= c; j++) {
                        stringBuilder1.append((d - 1));
                    }
                    int ynum1 = Integer.parseInt(stringBuilder1.toString());
                    return getAns(ynum1);
                }
            }
        }
    }

    public static void bfs(int r, int c, Queue<int[]> queue, long[][] dis, char[][] map, boolean[][] visited) {
        while (!queue.isEmpty()) {
            int[] ar = queue.poll();
            int x = ar[0];
            int y = ar[1];
            if (x + 1 < r) {
                if (map[x + 1][y] != 'T' && dis[x + 1][y] > (dis[x][y] + 1)) {
                    dis[x + 1][y] = Math.min(dis[x + 1][y], (dis[x][y] + 1));
                    queue.add(new int[]{x + 1, y});
                } /*else if (map[x][y] != map[x + 1][y] && dis[x + 1][y] > (dis[x][y] + 1)) {
                    dis[x + 1][y] = Math.min(dis[x + 1][y], dis[x][y] + 1);
                    queue.add(new int[]{x + 1, y});
                }*/
              /*  if(!visited[x+1][y] ){
                    queue.add(new int[]{x + 1, y});
                    visited[x+1][y]=true;
                }*/


            }
            if (y + 1 < c) {
                if (map[x][y + 1] != 'T' && dis[x][y + 1] > (dis[x][y] + 1)) {
                    dis[x][y + 1] = Math.min(dis[x][y + 1], dis[x][y] + 1);
                    queue.add(new int[]{x, y + 1});
                } /*else if (map[x][y] != map[x][y + 1] && dis[x][y + 1] > (dis[x][y] + 1)) {
                    dis[x][y + 1] = Math.min(dis[x][y + 1], dis[x][y] + 1);
                    queue.add(new int[]{x, y + 1});
                }*/
               /* if( !visited[x][y+1]){
                    queue.add(new int[]{x, y+1});
                    visited[x][y+1]=true;
                }*/


            }
            if (x - 1 >= 0) {
                if (map[x - 1][y] != 'T' && dis[x - 1][y] > (dis[x][y] + 1)) {
                    dis[x - 1][y] = Math.min(dis[x - 1][y], (dis[x][y] + 1));
                    queue.add(new int[]{x - 1, y});
                } /*else if (map[x][y] != map[x - 1][y] && dis[x - 1][y] > (dis[x][y] + 1)) {
                    dis[x - 1][y] = Math.min(dis[x - 1][y], dis[x][y] + 1);
                    queue.add(new int[]{x - 1, y});
                }*/
               /* if(!visited[x-1][y]){
                    queue.add(new int[]{x - 1, y});
                    visited[x-1][y]=true;
                }*/


            }
            if (y - 1 >= 0) {
                if (map[x][y - 1] != 'T' && dis[x][y - 1] > (dis[x][y] + 1)) {
                    dis[x][y - 1] = Math.min(dis[x][y - 1], (dis[x][y] + 1));
                    queue.add(new int[]{x, y - 1});
                } /*else if (map[x][y] != map[x][y - 1] && dis[x][y - 1] > (dis[x][y] + 1)) {
                    dis[x][y - 1] = Math.min(dis[x][y - 1], dis[x][y] + 1);
                    queue.add(new int[]{x, y - 1});
                }*/
               /* if(!visited[x][y-1]){
                    queue.add(new int[]{x , y-1});
                    visited[x][y-1]=true;
                }*/


            }
        }
    }


    public static void dfs1(List<List<Integer>> g, boolean[] visited, Stack<Integer> stack, int num) {
        visited[num] = true;
        for (Integer integer : g.get(num)) {
            if (!visited[integer]) {
                dfs1(g, visited, stack, integer);
            }
        }
        stack.push(num);
    }

    public static void dfs2(List<List<Integer>> g, boolean[] visited, List<Integer> list, int num, int c, int[] raj) {
        visited[num] = true;

        for (Integer integer : g.get(num)) {
            if (!visited[integer]) {
                dfs2(g, visited, list, integer, c, raj);
            }
        }
        raj[num] = c;
        list.add(num);

    }

    public static int inputInt() throws IOException {
        return sc.nextInt();
    }

    public static long inputLong() throws IOException {
        return sc.nextLong();
    }

    public static double inputDouble() throws IOException {
        return sc.nextDouble();
    }

    public static String inputString() throws IOException {
        return sc.readLine();
    }

    public static void print(String a) throws IOException {
        bw.write(a);
    }

    public static void printSp(String a) throws IOException {
        bw.write(a + " ");
    }

    public static void println(String a) throws IOException {
        bw.write(a + "\n");
    }


    public static long getAns(int[] ar, int c, long[][] dp, int i, int sign) {
        if (i < 0) {
            return 1;
        }

        if (c <= 0) {
            return 1;
        }

        dp[i][c] = Math.max(dp[i][c], Math.max(ar[i] * getAns(ar, c - 1, dp, i - 1, sign), getAns(ar, c, dp, i - 1, 1)));
        return dp[i][c];
    }


    public static long power(long a, long b, long c) {
        long ans = 1;
        while (b != 0) {
            if (b % 2 == 1) {
                ans = ans * a;
                ans %= c;
            }
            a = a * a;
            a %= c;
            b /= 2;
        }
        return ans;
    }

    public static long power1(long a, long b, long c) {
        long ans = 1;
        while (b != 0) {
            if (b % 2 == 1) {
                ans = multiply(ans, a, c);
            }
            a = multiply(a, a, c);
            b /= 2;

        }
        return ans;

    }

    public static long multiply(long a, long b, long c) {
        long res = 0;
        a %= c;
        while (b > 0) {
            if (b % 2 == 1) {
                res = (res + a) % c;
            }
            a = (a + a) % c;
            b /= 2;
        }

        return res % c;

    }

    public static long totient(long n) {
        long result = n;
        for (long i = 2; i * i <= n; i++) {
            if (n % i == 0) {
                //sum=sum+2*i;
                while (n % i == 0) {
                    n /= i;
                    // sum=sum+n;
                }
                result -= result / i;

            }
        }
        if (n > 1) {
            result -= result / n;

        }
        return result;
    }


    public static long gcd(long a, long b) {
        if (b == 0) {
            return a;
        } else {
            return gcd(b, a % b);
        }
    }

    public static boolean[] primes(int n) {
        boolean[] p = new boolean[n + 1];
        p[0] = false;
        p[1] = false;
        for (int i = 2; i <= n; i++) {
            p[i] = true;
        }

        for (int i = 2; i * i <= n; i++) {
            if (p[i]) {
                for (int j = i * i; j <= n; j += i) {
                    p[j] = false;
                }
            }

        }
        return p;
    }

}