### A Meaningless Problem

| Memory limit: | 64 megabytes |

Once upon a time, Glory was wandering in a mysterious forest. Suddenly, he was attracted by a
fascinating tree, which is surprisingly a perfect binary tree. There was an infinity numbers of
leaves on this tree. Glory was so curious that he wanted to know its structure in a meaningless
way. To fulfill his wish, let’s assume that its numbering is shown as the figure below. That is
to say, you need to help him answer the least common ancestor between two given
nodes.

#### Input

The input contains several test cases ending with EOF.

For each test case, only one line contains two integer a and b indicating the two nodes.

We guarantee that the length of a + b in the decimal code is up to 2 000 in one test, and the
total length of all a s and b s is up to 20 000.

#### Output

For each test case, output a line containing an integer indicating the least common ancestor
between two given nodes.

#### Sample Input

12 7

#### Sample Output

3