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 PyPy3 (2.4.0) (judge verdict: Accepted)

n,k=map(int,input().split())
s=list(input())
if s[k-1]=='A':
    s[k-1]='a'
elif s[k-1]=='B':
    s[k-1]='b'
else:
    s[k-1]='c'
ans=''
for i in range(n):
    ans+=s[i]
print(ans)