if let input = readLine(), let nums = input.split(separator: " ").compactMap({Int($0)}) as? [Int], nums.count == 2 {
    let A: Int = nums[0]
    var B: Int = nums[1]

    var count: Int = 1
    var flag: Bool = false
    while B >= A {
        if A == B {
            flag = true
            break
        }

        if B%2 == 0 {
            B /= 2
            count+=1
        }
        else if B%10 == 1 {
            B = (B-1)/10
            count+=1
        }
        else {
            break
        }
    }

    print(flag ? count : -1)
}