The modulo operator is a very commonly used operation in computer science. The result of taking ~A~ modulo ~B~ is equal to the remainder of ~A~ when divided by ~B~.

For her ICS homework, Mimi was asked to find the greatest result of ~A~ mod ~M~ for all integers ~A~ in the range ~1, 2, \dots, N~. Can you help Mimi do her homework?

Constraints

Subtask 1 [40%]

~1 \le N, M \le 10^5~

Subtask 2 [60%]

~1 \le N, M \le 10^9~

Input Specification

The first and only line of input will contain two space separated integers, ~N~ and ~M~.

Output Specification

The greatest result of ~A~ mod ~M~ for all integers ~A~ in the range ~1, 2, \dots, N~.

Sample Input

5 3

Sample Output

2