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)

nyuuryoku1 = gets()
S = gets()
N = nyuuryoku1[0].to_i
K = nyuuryoku1[2].to_i
i = 0
anser = ""
while (i < (K - 1)) do
	anser << S[i]
	i += 1
end
anser << S[i].downcase
i += 1
while (i < (N)) do
	anser << S[i]
	i += 1
end
puts anser