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: Wrong Answer)

s = gets
h = s[0..1].to_i
t = s[2..3].to_i
m = 1..12
case
  when m.include?(t) && m.include?(h)
    puts 'AMBIGUOUS'
  when h >= 0 && m.include?(t)
    puts 'YYMM'
  when t >= 0 && m.include?(h)
    puts 'MMYY'
  else
    puts 'NA'
end