N, K = map(int, input().split())
S = input()
print('{}{}{}'.format(S[:K - 1], S[K - 1].lower(), S[K:]))

9c26891a19228855d2f2f223872b5d185e029e25
<mask token>

<mask token>
print('{}{}{}'.format(S[:K - 1], S[K - 1].lower(), S[K:]))

N, K = map(int, input().split())
S = input()
print('{}{}{}'.format(S[:K - 1], S[K - 1].lower(), S[K:]))
