Baekjoon-16953-A to B

A,B = map(int, input().split())

infty = int(1e9)

def dfs(x,goal, n):
    if x > goal:
        return infty
    elif x == goal:
        return n
    else:
        return min(dfs(2*x,goal,n+1), dfs(10*x+1,goal,n+1))

ans = dfs(A,B,0)
if ans == infty:
    print(-1)
else:
    print(ans+1)