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 (1.42.0) (judge verdict: Accepted)

#![allow(non_snake_case)]
#![allow(unused_imports)]
#![allow(unreachable_code)]
#![allow(unused_variables)]

use proconio::marker::{Bytes, Chars};
use proconio::{fastout, input};

#[fastout]
fn main() {
    input! {
        N: usize,
        K: usize,
        mut S: Chars,
    }

    S[K - 1] = match S[K - 1] {
        'A' => 'a',
        'B' => 'b',
        'C' => 'c',
        c => c,
    };

    println!("{}", S.iter().collect::<String>());
}