import java.util.Scanner;

public class Main{

    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);

        // input
        int dmy = scan.nextInt();
        int index = scan.nextInt() - 1;
        char[] input = scan.next().toCharArray();
        switch(input[index]){
            case 'A':
                input[index] = 'a';
                break;
            case 'B':
                input[index] = 'b';
                break;
            case 'C':
                input[index] = 'c';
                break;
        }

        // answer
        for(int i = 0; i < input.length; i++){
            System.out.print(input[i]);
        }
        System.out.println("");


    }
} import java.util.Scanner; Scanner java.util public class Main{

    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);

        // input
        int dmy = scan.nextInt();
        int index = scan.nextInt() - 1;
        char[] input = scan.next().toCharArray();
        switch(input[index]){
            case 'A':
                input[index] = 'a';
                break;
            case 'B':
                input[index] = 'b';
                break;
            case 'C':
                input[index] = 'c';
                break;
        }

        // answer
        for(int i = 0; i < input.length; i++){
            System.out.print(input[i]);
        }
        System.out.println("");


    }
} Main public static void main(String[] args){
        Scanner scan = new Scanner(System.in);

        // input
        int dmy = scan.nextInt();
        int index = scan.nextInt() - 1;
        char[] input = scan.next().toCharArray();
        switch(input[index]){
            case 'A':
                input[index] = 'a';
                break;
            case 'B':
                input[index] = 'b';
                break;
            case 'C':
                input[index] = 'c';
                break;
        }

        // answer
        for(int i = 0; i < input.length; i++){
            System.out.print(input[i]);
        }
        System.out.println("");


    } main {
        Scanner scan = new Scanner(System.in);

        // input
        int dmy = scan.nextInt();
        int index = scan.nextInt() - 1;
        char[] input = scan.next().toCharArray();
        switch(input[index]){
            case 'A':
                input[index] = 'a';
                break;
            case 'B':
                input[index] = 'b';
                break;
            case 'C':
                input[index] = 'c';
                break;
        }

        // answer
        for(int i = 0; i < input.length; i++){
            System.out.print(input[i]);
        }
        System.out.println("");


    } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int dmy = scan.nextInt(); dmy scan.nextInt() scan.nextInt scan int index = scan.nextInt() - 1; index scan.nextInt() - 1 scan.nextInt() scan.nextInt scan 1 char[] input = scan.next().toCharArray(); input scan.next().toCharArray() scan.next().toCharArray scan.next() scan.next scan switch(input[index]){
            case 'A':
                input[index] = 'a';
                break;
            case 'B':
                input[index] = 'b';
                break;
            case 'C':
                input[index] = 'c';
                break;
        } input[index] input index case 'A': 'A' case 'A': input[index] = 'a' input[index] input index 'a' break; case 'B': 'B' case 'B': input[index] = 'b' input[index] input index 'b' break; case 'C': 'C' case 'C': input[index] = 'c' input[index] input index 'c' break; for(int i = 0; i < input.length; i++){
            System.out.print(input[i]);
        } int i = 0; int i = 0; i 0 i < input.length i input.length input input.length i++ i++ i {
            System.out.print(input[i]);
        } {
            System.out.print(input[i]);
        } System.out.print(input[i]) System.out.print System.out System System.out input[i] input i System.out.println("") System.out.println System.out System System.out "" String[] args args public class Main{

    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);

        // input
        int dmy = scan.nextInt();
        int index = scan.nextInt() - 1;
        char[] input = scan.next().toCharArray();
        switch(input[index]){
            case 'A':
                input[index] = 'a';
                break;
            case 'B':
                input[index] = 'b';
                break;
            case 'C':
                input[index] = 'c';
                break;
        }

        // answer
        for(int i = 0; i < input.length; i++){
            System.out.print(input[i]);
        }
        System.out.println("");


    }
} public class Main{

    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);

        // input
        int dmy = scan.nextInt();
        int index = scan.nextInt() - 1;
        char[] input = scan.next().toCharArray();
        switch(input[index]){
            case 'A':
                input[index] = 'a';
                break;
            case 'B':
                input[index] = 'b';
                break;
            case 'C':
                input[index] = 'c';
                break;
        }

        // answer
        for(int i = 0; i < input.length; i++){
            System.out.print(input[i]);
        }
        System.out.println("");


    }
} Main
import java.util.Scanner;

public class Main{

    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);

        // input
        int dmy = scan.nextInt();
        int index = scan.nextInt() - 1;
        char[] input = scan.next().toCharArray();
        switch(input[index]){
            case 'A':
                input[index] = 'a';
                break;
            case 'B':
                input[index] = 'b';
                break;
            case 'C':
                input[index] = 'c';
                break;
        }

        // answer
        for(int i = 0; i < input.length; i++){
            System.out.print(input[i]);
        }
        System.out.println("");


    }
}