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)

fn main() {
    let mut buf = String::new();
    std::io::stdin().read_line(&mut buf).unwrap();
    let mut iter = buf.split_whitespace();
    let n : usize = iter.next().unwrap().parse().unwrap();
    let k : usize = iter.next().unwrap().parse().unwrap();
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).unwrap();
    let mut s: Vec<char> = s.trim().chars().collect();
    s[k-1] = s[k-1].to_ascii_lowercase();
    print!("{}", s.iter().collect::<String>())
}