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