Problem:
Score : 100 points

Problem Statement

You are given a string S of length N consisting of A, B and C, and an integer K which is between 1 and N (inclusive).
Print the string S after lowercasing the K-th character in it.

Constraints

1 ≤ N ≤ 50

1 ≤ K ≤ N

S is a string of length N consisting of A, B and C.

Input

Input is given from Standard Input in the following format:

N K
S

Output

Print the string S after lowercasing the K-th character in it.

Sample Input 1

3 1
ABC

Sample Output 1

aBC

Sample Input 2

4 3
CABA

Sample Output 2

CAbA

Solution in Python (3.4.3) (judge verdict: Accepted)

N, K = list(map(int,input().split()))
S = input()
ls = list(S)
if ls[K-1] == 'A':
  ls[K-1] = 'a'
elif ls[K-1] == 'B':
  ls[K-1] = 'b'
elif ls[K-1] == 'C':
  ls[K-1] = 'c'
print(''.join(ls))