N,K=map(int,input().split())
S=input()
s=list(S)
s[K-1]=s[K-1].lower()
a=''.join(s)
print(a) N,K=map(int,input().split()) N map(int,input().split()) map int input().split() ().split () input split K S=input() S input() input s=list(S) s list(S) list S s[K-1]=s[K-1].lower() s[K-1] s K-1 K 1 s[K-1].lower() [K-1].lower [K-1] s K-1 K 1 lower a=''.join(s) a ''.join(s) ''.join '' join s print(a) print a S=input() input() S a=''.join(s) ''.join(s) a N,K=map(int,input().split()) map(int,input().split()) N s=list(S) list(S) s K=map(int,input().split()) map(int,input().split()) K
N,K=map(int,input().split())
S=input()
s=list(S)
s[K-1]=s[K-1].lower()
a=''.join(s)
print(a)