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)

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

#[fastout]
fn main() {
    input! {
        n: usize,
        k: usize,
        s: String,
    }

    let mut ans = String::default();
    let k = k-1;

    for (i,c) in s.chars().enumerate(){
        if i==k {
            ans.push(c.to_lowercase().nth(0).unwrap());
        }
        else {
            ans.push(c);
        }
    }

    println!("{}",ans);
}