n,k = map(int, input().split())
s = str(input())
count = 0
for i in range(n):
    if count == k - 1:
        print(s[k - 1].lower(),end = "")
        count += 1
    else:
        print(s[count],end = "")
        count += 1 n,k = map(int, input().split()) n map(int, input().split()) map int input().split() ().split () input split k s = str(input()) s str(input()) str input() input count = 0 count 0 for i in range(n):
    if count == k - 1:
        print(s[k - 1].lower(),end = "")
        count += 1
    else:
        print(s[count],end = "")
        count += 1 i range(n) range n if count == k - 1:
        print(s[k - 1].lower(),end = "")
        count += 1
    else:
        print(s[count],end = "")
        count += 1 count == k - 1 count k - 1 k 1 print(s[k - 1].lower(),end = "") print s[k - 1].lower() [k - 1].lower [k - 1] s k - 1 k 1 lower end = "" end "" count += 1 count 1 print(s[count],end = "") print s[count] s count end = "" end "" count += 1 count 1 k = map(int, input().split()) map(int, input().split()) k s = str(input()) str(input()) s count += 1 1 count count = 0 0 count n,k = map(int, input().split()) map(int, input().split()) n count += 1 1 count
n,k = map(int, input().split())
s = str(input())
count = 0
for i in range(n):
    if count == k - 1:
        print(s[k - 1].lower(),end = "")
        count += 1
    else:
        print(s[count],end = "")
        count += 1