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())
s = input()
ans = ""
for i in range(N):
    if i==K-1:
        if s[i]=="A":
            a = "a"
        elif s[i] == "B":
            a = "b"
        else:
            a = "c"
        ans += a
    else:
        ans += s[i]
print(ans)