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 C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Linq;
using System.Collections.Generic;

namespace abc081b{
    class Program{
        static void Main (string[] args){
            var vs = Console.ReadLine().Split().Select(x=>int.Parse(x)).ToArray();
            var s = Console.ReadLine();
            int n = vs[0];
            int k = vs[1];
            string ans="";
            for(int i =0;i<n;i++){
                if(i==k-1){
                    ans += char.ToLower(s[i]);
                }
                else{
                    ans += s[i];
                }
            }
            Console.WriteLine(ans);
        }
    }
}