n, k = map(int, input().split())
s = str(input())
for i in range(n):
    if i + 1 == k:
        if s[i] == 'A':
            print('a', end='')
        elif s[i] == 'B':
            print('b', end='')
        else:
            print('c', end='')
    else:
        print(s[i], end='') n, k = map(int, input().split()) n map(int, input().split()) map int input().split() ().split () input split k s = str(input()) s str(input()) str input() input for i in range(n):
    if i + 1 == k:
        if s[i] == 'A':
            print('a', end='')
        elif s[i] == 'B':
            print('b', end='')
        else:
            print('c', end='')
    else:
        print(s[i], end='') i range(n) range n if i + 1 == k:
        if s[i] == 'A':
            print('a', end='')
        elif s[i] == 'B':
            print('b', end='')
        else:
            print('c', end='')
    else:
        print(s[i], end='') i + 1 == k i + 1 i 1 k if s[i] == 'A':
            print('a', end='')
        elif s[i] == 'B':
            print('b', end='')
        else:
            print('c', end='')
     s[i] == 'A' s[i] s i 'A' print('a', end='') print 'a' end='' end '' elif s[i] == 'B':
            print('b', end='')
         s[i] == 'B' s[i] s i 'B' print('b', end='') print 'b' end='' end '' print('c', end='') print 'c' end='' end '' print(s[i], end='') print s[i] s i end='' end '' n, k = map(int, input().split()) map(int, input().split()) n s = str(input()) str(input()) s k = map(int, input().split()) map(int, input().split()) k
n, k = map(int, input().split())
s = str(input())
for i in range(n):
    if i + 1 == k:
        if s[i] == 'A':
            print('a', end='')
        elif s[i] == 'B':
            print('b', end='')
        else:
            print('c', end='')
    else:
        print(s[i], end='')