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

ss=s[k-1]
p=ss.lower()
#print(p)
s[k-1]=p
#print(s[k-1])
#print(s)

ans="".join(s)
print(ans) n,k=map(int, input().split()) n map(int, input().split()) map int input().split() ().split () input split k s=list(input()) s list(input()) list input() input ss=s[k-1] ss s[k-1] s k-1 k 1 p=ss.lower() p ss.lower() ss.lower ss lower s[k-1]=p s[k-1] s k-1 k 1 p ans="".join(s) ans "".join(s) "".join "" join s print(ans) print ans s=list(input()) list(input()) s k=map(int, input().split()) map(int, input().split()) k ans="".join(s) "".join(s) ans n,k=map(int, input().split()) map(int, input().split()) n p=ss.lower() ss.lower() p ss=s[k-1] s[k-1] ss
n,k=map(int, input().split())
s=list(input())

ss=s[k-1]
p=ss.lower()
#print(p)
s[k-1]=p
#print(s[k-1])
#print(s)

ans="".join(s)
print(ans)