Vasya will fancy any number as long as it is an integer power of two. Petya, on the other hand, is very conservative and only likes a single integer p (which may be positive, negative, or zero). To combine their tastes, they invented p-binary numbers of the form 2^x + p, where x is a non-negative integer.

For example, some -9-binary ("minus nine" binary) numbers are: -8 (minus eight), 7 and 1015 (-8=2^0-9, 7=2^4-9, 1015=2^{10}-9).

The boys now use p-binary numbers to represent everything. They now face a problem: given a positive integer n, what's the smallest number of p-binary numbers (not necessarily distinct) they need to represent n as their sum? It may be possible that representation is impossible altogether. Help them solve this problem.

For example, if p=0 we can represent 7 as 2^0 + 2^1 + 2^2.

And if p=-9 we can represent 7 as one number (2^4-9).

Note that negative p-binary numbers are allowed to be in the sum (see the Notes section for an example).

Input

The only line contains two integers n and p (1 ≤ n ≤ 10^9, -1000 ≤ p ≤ 1000).

Output

If it is impossible to represent n as the sum of any number of p-binary numbers, print a single integer -1. Otherwise, print the smallest possible number of summands.

Examples

Input


24 0


Output


2


Input


24 1


Output


3


Input


24 -1


Output


4


Input


4 -7


Output


2


Input


1 1


Output


-1

Note

0-binary numbers are just regular binary powers, thus in the first sample case we can represent 24 = (2^4 + 0) + (2^3 + 0).

In the second sample case, we can represent 24 = (2^4 + 1) + (2^2 + 1) + (2^0 + 1).

In the third sample case, we can represent 24 = (2^4 - 1) + (2^2 - 1) + (2^2 - 1) + (2^2 - 1). Note that repeated summands are allowed.

In the fourth sample case, we can represent 4 = (2^4 - 7) + (2^1 - 7). Note that the second summand is negative, which is allowed.

In the fifth sample case, no representation is possible.
import java.io.*;
import java.util.*;

import static java.lang.Math.*;


@SuppressWarnings("Duplicates")

public class solveLOL {
    FastScanner in;
    PrintWriter out;
    boolean systemIO = true, multitests = false;


    void solve() {
        int n = in.nextInt(), p = in.nextInt();
        for (int i = 0; i < 5000 && n - i * p >= i; i++) {
            if (check(n - i * p, i) == 1) {
                System.out.println(i);
                System.exit(0);
            }
        }
        System.out.println("-1");
    }

    int check(int x, int p) {
        int count = 0;
        while (x > 0) {
            if (x % 2 == 1) {
                count++;
            }
            x /= 2;
        }
        if (count <= p) {
            return 1;
        } else {
            return -1;
        }
    }


    class FastScanner {
        BufferedReader br;
        StringTokenizer st;

        FastScanner(File f) {
            try {
                br = new BufferedReader(new FileReader(f));
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            }
        }

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

        String nextLine() {
            try {
                return br.readLine();
            } catch (IOException e) {
                return null;
            }
        }

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

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

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

        double nextDouble() {
            return Double.parseDouble(next());
        }

    }

    //String.format("%8.3f", ans).replace(',', '.')
    private void run() throws IOException {
        if (systemIO) {
            in = new solveLOL.FastScanner(System.in);
            out = new PrintWriter(System.out);
        } else {
            in = new solveLOL.FastScanner(new File("INPUT.txt"));
            out = new PrintWriter(new File("OUTPUT.txt"));
        }
        for (int t = multitests ? in.nextInt() : 1; t-- > 0; )
            solve();

        out.close();
    }

    public static void main(String[] arg) throws IOException {
        new solveLOL().run();
    }

}