n,k=map(int,input().split())
s=input()
if s[k-1]=="A":
    print(s[:k-1]+"a"+s[k:])
elif s[k-1]=="B":
    print(s[:k-1]+"b"+s[k:])
else:
    print(s[:k-1]+"c"+s[k:]) n,k=map(int,input().split()) n map(int,input().split()) map int input().split() ().split () input split k s=input() s input() input if s[k-1]=="A":
    print(s[:k-1]+"a"+s[k:])
elif s[k-1]=="B":
    print(s[:k-1]+"b"+s[k:])
else:
    print(s[:k-1]+"c"+s[k:]) s[k-1]=="A" s[k-1] s k-1 k 1 "A" print(s[:k-1]+"a"+s[k:]) print s[:k-1]+"a"+s[k:] s[:k-1]+"a" s[:k-1] s :k-1 k-1 k 1 "a" s[k:] s k: k elif s[k-1]=="B":
    print(s[:k-1]+"b"+s[k:]) s[k-1]=="B" s[k-1] s k-1 k 1 "B" print(s[:k-1]+"b"+s[k:]) print s[:k-1]+"b"+s[k:] s[:k-1]+"b" s[:k-1] s :k-1 k-1 k 1 "b" s[k:] s k: k print(s[:k-1]+"c"+s[k:]) print s[:k-1]+"c"+s[k:] s[:k-1]+"c" s[:k-1] s :k-1 k-1 k 1 "c" s[k:] s k: k n,k=map(int,input().split()) map(int,input().split()) n k=map(int,input().split()) map(int,input().split()) k s=input() input() s
n,k=map(int,input().split())
s=input()
if s[k-1]=="A":
    print(s[:k-1]+"a"+s[k:])
elif s[k-1]=="B":
    print(s[:k-1]+"b"+s[k:])
else:
    print(s[:k-1]+"c"+s[k:])