Sabzeh with Lentils

Parsa's Grandmother has prepared a row of $n$ planting positions, numbered from $1$ to $n$. She wants to plant exactly $k$ lentil seeds in these positions.

At most one seed can be planted in each position.

If two consecutive positions both contain a seed, that creates one adjacent occupied pair. Grandmother wants to place the $k$ seeds so that the number of adjacent occupied pairs is as small as possible.

Compute this minimum possible number.

Input

The input contains two integers, $n$ the number of positions and $k$, the number of lentil seeds.

Output

Print a single integer: the minimum possible number of adjacent occupied pairs.

Constraints

• $2 \le n \le 100$
• $1 \le k \le n$

Example 1

5 2

0

Example 2

5 4

2