n, k = list(map(int, input().split()))
s=input()

before = s[0:k-1]
low = s[k-1]
low = low.lower()
after = s[k:]

print(before+low+after) n, k = list(map(int, input().split())) n list(map(int, input().split())) list map(int, input().split()) map int input().split() ().split () input split k s=input() s input() input before = s[0:k-1] before s[0:k-1] s 0:k-1 0 k-1 k 1 low = s[k-1] low s[k-1] s k-1 k 1 low = low.lower() low low.lower() low.lower low lower after = s[k:] after s[k:] s k: k print(before+low+after) print before+low+after before+low before low after s=input() input() s after = s[k:] s[k:] after k = list(map(int, input().split())) list(map(int, input().split())) k before = s[0:k-1] s[0:k-1] before low = low.lower() low.lower() low low = s[k-1] s[k-1] low n, k = list(map(int, input().split())) list(map(int, input().split())) n
n, k = list(map(int, input().split()))
s=input()

before = s[0:k-1]
low = s[k-1]
low = low.lower()
after = s[k:]

print(before+low+after)