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 get_input() -> String {
    let mut word = String::new();
    std::io::stdin().read_line(&mut word).unwrap();
    word.trim().to_owned()
}

fn main() {
    let (_n, k) = {
        let line = get_input();
        let mut split = line.split_whitespace();
        let n:u64 = split.next().unwrap().parse().unwrap();
        let k:u64 = split.next().unwrap().parse().unwrap();
        (n, k)
    };

    let mut s:Vec<char> = get_input().chars().collect();
    let i = (k - 1) as usize;
    s[i] = s[i].to_lowercase().next().unwrap();

    let ans: String = s.into_iter().collect();
    println!("{}", ans);
}