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.chomp
a = s[0..1].to_i
b = s[2..3].to_i
if (a == 00 || b == 00) || (a > 12 && b > 12)
  puts "NA"
elsif a <= 12 && b <=12
  puts "AMBIGUOUS"
elsif  b >=12
  puts "MMYY"
elsif  a >= 12
  puts "YYMM"
end