N,K=map(int,input().split())
S=input()
s=S[:K-1]
s+=S[K-1].swapcase()
s+=S[K:]
print(s) 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=S[:K-1] s S[:K-1] S :K-1 K-1 K 1 s+=S[K-1].swapcase() s S[K-1].swapcase() [K-1].swapcase [K-1] S K-1 K 1 swapcase s+=S[K:] s S[K:] S K: K print(s) print s s+=S[K:] S[K:] s s+=S[K-1].swapcase() S[K-1].swapcase() s N,K=map(int,input().split()) map(int,input().split()) N s=S[:K-1] S[:K-1] s K=map(int,input().split()) map(int,input().split()) K S=input() input() S
N,K=map(int,input().split())
S=input()
s=S[:K-1]
s+=S[K-1].swapcase()
s+=S[K:]
print(s)