t1748

import java.util.LinkedList;
import java.util.Scanner;

public class t1748 {
    static Scanner in = new Scanner(System.in);
    static int start = in.nextInt();
    static int end = in.nextInt();
    static int [][] a = new int [end+1][end+1];
    static int inf = Integer.MIN_VALUE;
    static int [] dist = new int [end+1];
    static LinkedList<Integer> queue = new LinkedList<Integer>();

    public static void array(int start, int end) {
        for (int i = 1; i < end+1; i++) {
            for (int j = 1; j < end+1; j++) {
                if(j == i+3 || j == i*4) {
                    a[i][j] = 1;
                }
            }
        }
    }

    public static void bfs(int s) {
        dist[s]=0;
        queue.addLast(s);
        int v;

        while(queue.isEmpty() == false) {
            v = queue.pollFirst();
            for (int i = 1; i < end+1; i++) {
                if(a[v][i] == 1 && dist[i] == inf) {
                    dist[i] = dist[v] + 1;
                    queue.addLast(i);
                }
            }

        }
    }

    public static void main(String[] args) {
        if(start > end)
            System.out.println(-1);
        else {
        for (int i = 1; i < end+1; i++) {
            dist[i] = inf;
        }

        array(start, end);
        bfs(start);


        if(dist[end] != inf)
        System.out.println(dist[end]);
        else
            System.out.println(-1);
        }
}}