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 Haskell (GHC 7.10.3) (judge verdict: Accepted)

import Data.Char

main :: IO()
main = do
    [n, k] <- map read . words <$> getLine
    s <- getLine
    let f = take (k-1) s
    let c = s !! (k-1)
    let lowerc = toLower c
    let cs = [lowerc]
    let b = drop k s
    let o = f ++ cs ++ b
    putStr o