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) {
	tmp = input.split("\n");
	var a = tmp[0].split(" ");
	var n = parseInt(a[0]);
	var k = parseInt(a[1])-1;
	var s = tmp[1];
	var r = "";
	for (var i = 0 ; i < n ; i++){
		if(i==k){
			if(s.charAt(i) == "A"){ r += "a"; }
			if(s.charAt(i) == "B"){ r += "b"; }
			if(s.charAt(i) == "C"){ r += "c"; }
		}else{
			r += s.charAt(i);
		}
	}
	console.log(r);
}

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