class Solution:
def characterReplacement(self, s: str, k: int) -> int:
left =0
right =0
result=0
character_cnt= {}
max_freq =0
while right<len(s):
character_cnt[s[right]] = character_cnt.get(s[right], 0) + 1
max_freq =max(max_freq,character_cnt[s[right]])
while (right-left+1 -max_freq) > k :
character_cnt[s[left]]-=1
left +=1
result = max(result,right-left+1)
right +=1
return result