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 = STDIN.gets.chomp.split(' ').map(&:to_i)
s = STDIN.gets.chomp

s.each_char.with_index{ |c, i|
  if i+1 == K then
    if c == 'A' then
      print 'a'
    elsif c == 'B'
      print 'b'
    else
      print 'c'
    end
  else
    print c
  end
}

puts