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

Input

5 2

Output

0

Example 2

Input

5 4

Output

2