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 JavaScript (node.js v5.12) (judge verdict: Accepted)

"use strict";

const stringToIntDecimal = s => parseInt(s);

const readData = input => {
  const inputArray = input.split("\n");
  const numberArray = inputArray[0].split(" ").map(stringToIntDecimal);

  return {
    length: numberArray[0],
    operandNumber: numberArray[1],
    str: inputArray[1]
  };
};

function Main(input) {
  let data = readData(input);
  const index = data.operandNumber - 1;
  const inputString = data.str;
  let outputString =
    inputString.substring(0, index) +
    inputString.charAt(index).toLowerCase() +
    inputString.substring(index + 1, data.length);
  console.log(outputString);
}

Main(require("fs").readFileSync("/dev/stdin", "utf8"));