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)

N, K = gets.chomp.split.map(&:to_i)
S = gets.chomp.split('')

def replace(s, k)
  if s[k - 1] == 'A'
    s[k - 1] = 'a'
  elsif s[k - 1] == 'B'
    s[k - 1] = 'b'
  else
    s[k - 1] = 'c'
  end
end

replace(S, K)

puts S.join