n, k = input().split()
a = int(n)
b = int(k)
s = input()
result = ''
for i in range(a):
    if i == b-1:
        result += chr(ord(s[i]) + 32)
    else:
        result += s[i]
print(result) n, k = input().split() n input().split() ().split () input split k a = int(n) a int(n) int n b = int(k) b int(k) int k s = input() s input() input result = '' result '' for i in range(a):
    if i == b-1:
        result += chr(ord(s[i]) + 32)
    else:
        result += s[i] i range(a) range a if i == b-1:
        result += chr(ord(s[i]) + 32)
    else:
        result += s[i] i == b-1 i b-1 b 1 result += chr(ord(s[i]) + 32) result chr(ord(s[i]) + 32) chr ord(s[i]) + 32 ord(s[i]) ord s[i] s i 32 result += s[i] result s[i] s i print(result) print result s = input() input() s result += s[i] s[i] result n, k = input().split() input().split() n result = '' '' result k = input().split() input().split() k result += chr(ord(s[i]) + 32) chr(ord(s[i]) + 32) result a = int(n) int(n) a b = int(k) int(k) b
n, k = input().split()
a = int(n)
b = int(k)
s = input()
result = ''
for i in range(a):
    if i == b-1:
        result += chr(ord(s[i]) + 32)
    else:
        result += s[i]
print(result)