a,b=list(map(int,input().split()))
cnt = 0
while (not a == b) and b > 0:
if b %10 ==1:
b//=10
cnt+=1
elif b % 2 ==0:
b//=2
cnt+=1
else:
print(-1)
break
else:
if b <= 0:
print(-1)
else:
print(cnt+1)