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()

s_dic = {"A":"a", "B":"b", "C":"c", "D":"d",
         "E":"e", "F":"f", "G":"g", "H":"h",
         "I":"i", "J":"j", "K":"k", "L":"l",
         "M":"m", "N":"n", "O":"o", "P":"p", "Q":"q",
         "R":"r", "S":"s", "T":"t", "U":"u",
         "V":"v", "W":"w", "X":"x", "Y":"y", "Z":"z"
        }

output = ""
for i in range(len(S)):
    if i == K - 1:
        output += s_dic[S[i]]
    else:
        output += S[i]

print(output)