2.1 The Secret Code of the Binary Knights

Score: 10pts

Time Limit: 5.00 sec

In Bitville, Ada, a young aspiring Binary Knight, was given a challenge by her mentor, Master Rajneel. To prove herself, she must uncover the strongest bond between two numbers, m and n, where m ≤ x < y ≤ n.

The bond's strength would be the highest value obtained by applying the first operation that reveals the differences between numbers, followed by the second operation that highlights the similarities between the result and one of those original numbers.

Can you help Ada decipher the secret code and prove herself worthy of becoming a Binary Knight?

The bond's strength would be the highest value obtained by applying the first operation that reveals the differences between numbers, followed by the second operation that highlights the similarities between the result and one of those original numbers.

Can you help Ada decipher the secret code and prove herself worthy of becoming a Binary Knight?

Constraints

m and n (1 ≤ m < n ≤ 9).

Input Format

A single line containing two space-separated single-digit positive integers

Output Format

A single-digit non-negative integer.

Example 1

Input:

3 5

Output:

4

Explanation:

The "similarities" of 3 and 5 result in a certain number,we select the greater value between the "differences" of input elements(3,5) and the certain number we obtained earlier

3 5

Output:

4

Explanation:

The "similarities" of 3 and 5 result in a certain number,we select the greater value between the "differences" of input elements(3,5) and the certain number we obtained earlier