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.util.*;
import java.lang.*;
import java.io.*;

// Created by @thesupremeone on 19/07/21
public class PBinary {
    boolean exists(long n, int steps){
        long mask = 1;
        int count = 0;
        while (mask<n){
            if((mask&n)!=0){
                count++;
            }
            mask <<= 1;
        }
        if(count>steps) return false;
        else if(count==steps) return true;
        return steps<=n;
    }
    void solve() throws IOException {
        long n = getLong();
        int p = getInt();
        int steps = 0;
        boolean found = n>p;
        while (found){
            if(n<=0){
                found = false;
                break;
            }
            n -= p;
            steps++;
            if(exists(n, steps))
                break;
        }
        if(found){
            println(steps);
        }else {
            println(-1);
        }
    }

    public static void main(String[] args) throws Exception {
        if (isOnlineJudge()) {
            in = new BufferedReader(new InputStreamReader(System.in));
            out = new BufferedWriter(new OutputStreamWriter(System.out));
            new PBinary().solve();
            out.flush();
        } else {
            localJudge = new Thread();
            in = new BufferedReader(new FileReader("input.txt"));
            out = new BufferedWriter(new FileWriter("output.txt"));
            localJudge.start();
            new PBinary().solve();
            out.flush();
            localJudge.suspend();
        }
    }
    static boolean isOnlineJudge(){
        try {
            return System.getProperty("ONLINE_JUDGE")!=null
                    || System.getProperty("LOCAL")==null;
        }catch (Exception e){
            return true;
        }
    }
    // Fast Input & Output
    static Thread localJudge = null;
    static BufferedReader in;
    static StringTokenizer st;
    static BufferedWriter out;
    static String getLine() throws IOException{
        return in.readLine();
    }
    static String getToken() throws IOException{
        if(st==null || !st.hasMoreTokens())
            st = new StringTokenizer(getLine());
        return st.nextToken();
    }
    static int getInt() throws IOException {
        return Integer.parseInt(getToken());
    }
    static long getLong() throws IOException {
        return Long.parseLong(getToken());
    }
    static void print(Object s) throws IOException{
        out.write(String.valueOf(s));
    }
    static void println(Object s) throws IOException{
        out.write(String.valueOf(s));
        out.newLine();
    }
}