A genome-style tape is a string s of lowercase letters. For a chosen letter c, scan every contiguous substring of exactly k characters and report the greatest number of times c appears inside any single such window.
Input format
Line 1: an integer k and a single lowercase letter c, separated by a space.
Line 2: the string s (lowercase English letters, no spaces).
Output format
A single integer: the maximum number of occurrences of c in any length-k substring of s.
Constraints
- 1 ≤ k ≤ |s| ≤ 100000
sconsists of lowercase English letters only.cis a single lowercase English letter.