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: Wrong Answer)

N , K = map(int, input().split())
S     = input()

ls = []

for n in range(N):
	ls.append(S[n])

result = ""

for n in range(N):
	if n != K-1:
		result += ls[n]
	else:
		if S[K-1] == "A":
			result += "a"
		if S[K-1] == "B":
			result += "b"
		if S[K-1] == "C":
			result += "ac"

print(result)