Math Practice
题号:NC24744
时间限制:C/C++/Rust/Pascal 1秒,其他语言2秒
空间限制:C/C++/Rust/Pascal 32 M,其他语言64 M
64bit IO Format: %lld

题目描述

One lovely afternoon, Bessie's friend Heidi was helping Bessie review for her upcoming math exam.
Heidi presents two integers A (0 <= A <= 45) and B (1 <= B <= 9) to Bessie who must respond with an integer E in the range 1..62. E is the smallest integer in that range that is strictly greater than A and also has B as the first digit of 2 raised to the E-th power. If there is no answer, Bessie responds with 0.
Help Bessie correctly answer all of Heidi's questions by calculating her responses.
By way of example, consider A=1 and B=6. Bessie might generate a table like this:
         E         2^E    First digit of 2^E
         2          4            4
         3          8            8
         4         16            1
         5         32            3
         6         64            6      <-- matches B
Thus, E=6 is the proper answer.
NOTE: The value of 2^44 does not fit in a normal 32-bit integer.

输入描述:

* Line 1: Two space-separated integers: A and B

输出描述:

* Line 1: A single integer E calculated as above
示例1

输入

复制
1 6 

输出

复制
6