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)

function Main(input){
    var xs = input.split('\n');
    //console.log(xs);
    var nums = xs[0].split(' ').map(v => parseInt(v, 10));
    //console.log(nums);
    var K = nums[1];
    var S = xs[1];
    var a = S.slice(0, K -1 );
    var b = S[K -1].toLowerCase(); 
    var c = S.slice(K);
    console.log(a+b+c);
  
}
Main(require("fs").readFileSync("/dev/stdin","utf8"));