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)

array = gets.split.map(&:to_i)
string = gets.chomp
if array[1] == 1
  hoge = string[0].downcase + string[array[1]...array[0]]
elsif array[0] == array[1]
  hoge = string[0...array[0]-1] + string[array[0]-1].downcase
else
  hoge = string[0...array[1]-1] + string[array[1]-1].downcase + string[array[1]...array[0]]
end
puts hoge