You are given a string ~B~ of length ~n~ (called a block), where each character ~B_i~ is either W or B, representing a white block or a black block at position ~i~, respectively.

You are also given an integer ~k~, representing the desired number of consecutive black blocks.

In one operation, you are allowed to change a white block W into a black block B.

Task: Determine the minimum number of operations required so that the string contains at least one segment of ~k~ consecutive black blocks.

Input

• The first line contains the string ~B~ (consisting of characters W and B) of length ~n~.
• The second line contains an integer ~k~.

Output

• An interger which is the minimum number of operations required.

Sample Input

WBBWWBBWBW
7

Sample Output

2