x, y = map(int, input().split())
z = list(input())
z[y-1] = z[y-1].lower()
print("".join(z))
 x, y = map(int, input().split()) x map(int, input().split()) map int input().split() ().split () input split y z = list(input()) z list(input()) list input() input z[y-1] = z[y-1].lower() z[y-1] z y-1 y 1 z[y-1].lower() [y-1].lower [y-1] z y-1 y 1 lower print("".join(z)) print "".join(z) "".join "" join z y = map(int, input().split()) map(int, input().split()) y z = list(input()) list(input()) z x, y = map(int, input().split()) map(int, input().split()) x
x, y = map(int, input().split())
z = list(input())
z[y-1] = z[y-1].lower()
print("".join(z))

