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 Ruby (2.3.3) (judge verdict: Accepted)

str1 = gets.split
N,K = str1[0].to_i, str1[1].to_i

S = gets.chomp

if S[K-1] == "A"
  S[K-1] = "a"
elsif S[K-1] == "B"
  S[K-1] = "b"
else
  S[K-1] = "c"
end

puts S