class Solution:
    def minimumRecolors(self, blocks: str, k: int) -> int:
        minimum = float('inf')
        
        i = 0
        while i <= (len(blocks) - k):
            count =  blocks[i:i+k].count('W')
            if count < minimum: 
                minimum = count
            i += 1 
        
        return minimum if minimum < float('inf') else 0