Input

5 17

Output

4

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<string>
 4 #include<cstring>
 5 #include<algorithm>
 6 #include<cmath>
 7 using namespace std;
 8 int n, k;
 9 int book[100010];
10 struct student
11 {
12     int x, step;
13 }que[100010];
14 bool  check(int x)
15 {
16     if (x < 0 || x>100000 || book[x] == 1)
17         return 0;
18     return 1;
19 }
20 int bfs()
21 {
22     if (n == k)    return 0;
23     book[n] = 1;
24     int head = 1, tail = 2;
25     que[head].x = n;
26     que[head].step = 0;
27     while (head < tail) {
28         int tx1 = que[head].x - 1;
29         if (check(tx1))
30         {
31             que[tail].x = tx1;
32             que[tail].step = que[head].step + 1;
33             book[tx1] = 1;
34             if (tx1 == k)
35                 return que[tail].step;
36             tail++;
37         }
38         int tx2 = que[head].x + 1;
39         if (check(tx2))
40         {
41             que[tail].x = tx2;
42             que[tail].step = que[head].step + 1;
43             book[tx2] = 1;
44             if (tx2 == k)
45                 return que[tail].step;
46             tail++;
47         }
48         int tx3 = que[head].x * 2;
49         if (check(tx3))
50         {
51             que[tail].x = tx3;
52             que[tail].step = que[head].step + 1;
53             book[tx3] = 1;
54             if (tx3 == k)
55                 return que[tail].step;
56             tail++;
57         }
58         head++;
59     }
60 }
61 int main()
62 {
63     cin >> n >> k;
64     cout << bfs() << endl;
65     return 0;
66 }