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 Rust (1.15.1) (judge verdict: Accepted)

use std::io::stdin;

fn main () {
    let mut nk = String::new();
    stdin().read_line(&mut nk).unwrap();
    let nk: Vec<usize> = nk.trim().split_whitespace().flat_map(str::parse).collect();
    let mut s = String::new();
    stdin().read_line(&mut s).unwrap();


    let (n, k) = (nk[0], nk[1]);
    let s: String = s.trim().chars().enumerate().map(|(i, c)| if i + 1 == k { (c as u8 + 32) as char } else { c }).collect();
    println!("{}", s);
}