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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

//package com.karancp;

import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.*;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.BufferedReader;
import java.io.InputStream;


 class Main {
    public static void main(String args[])
    {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader z = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        task solver =new task();
        solver.solve(z,out);
        out.close();
    }

    static class task
    {

        static long gcd(long a,long b)
        {
            if(b==0)return a;
            else return gcd(b,a%b);
        }
        static long lcm(long a,long b)
        {
            long pp=a*b;
            long bb=gcd(a,b);
            long res =pp/bb;
            return res;
        }
        static int max(int a,int b)
        {
            return Math.max(a,b);
        }
        static int min(int a,int b)
        {
            return Math.min(a,b);
        }





        public static void solve(InputReader z, PrintWriter out) {
           int n=z.nextInt();
           int k=z.nextInt();
           char ar[]=z.next().toCharArray();
           ar[k-1]=(char)(ar[k-1]+32);
           int i;
           for(i=0;i<n;i++)out.print(ar[i]);
        }
    }
    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }
        public long nextLong() {
            return Long.parseLong(next());
        }

    }



}