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 (2.7.6) (judge verdict: Accepted)

# -*- coding: utf-8 -*-
# スペース区切りの整数の入力
n, k = map(int, raw_input().split())

# 文字列の入力
str = list(raw_input())

str[k-1] = str[k-1].lower()
# 出力
newstr = "".join(str)
print(newstr)