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 = map(int,input().split())
K = K-1
S = input()
S_list = list(S)
if S_list[K] == "A":
  S_list[K] = "a"
elif S_list[K] == "B":
  S_list[K] = "b"
else:
  S_list[K] = "c"

S_changed = "".join(S_list)
print(S_changed)