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)

fn read_line() -> String {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).unwrap();
    s.trim_right().to_owned()
}

fn main() {
    let v: Vec<usize> = read_line().split_whitespace().map(|x| x.parse().unwrap()).collect();
    let (_, k) = (v[0], v[1] - 1);

    let mut chars: Vec<_> = read_line().chars().map(|c| c.to_string()).collect();
    chars[k] = chars[k].to_lowercase();
    
    println!("{}", chars.join(""));
}