백준 16953

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.LinkedList;
import java.util.Queue;
import java.util.StringTokenizer;

class Main16953 {

   public static void main(String[] args) throws Exception {
      BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      StringTokenizer st = new StringTokenizer(br.readLine());

      int A = Integer.parseInt(st.nextToken());
      int B = Integer.parseInt(st.nextToken());

      int answer = go(A, B);
      System.out.println(answer);
   }

   private static int go(int a, int b) {
      int count = -1;

      Queue<Pair> q = new LinkedList<>();
      q.add(new Pair(a, 1));

      while (!q.isEmpty()) {
         Pair p = q.poll();

         if (p.result == b) {
            count = p.count;
            break;
         }

         long multiply = p.result * 2;
         long add = (p.result * 10) + 1;

         if (multiply <= b) {
            q.add(new Pair(multiply, p.count + 1));
         }

         if (add <= b) {
            q.add(new Pair(add, p.count + 1));
         }
      }

      return count;
   }

   private static class Pair {
      long result;
      int count;

      public Pair(long result, int count) {
         this.result = result;
         this.count = count;
      }
   }
}