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