import java.util.Scanner;

public class Main {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        int K = sc.nextInt();

        String S = sc.next();
        
        String[] strArray = S.split("");
        strArray[K-1] = strArray[K-1].toLowerCase();

        for(int i=0; i < strArray.length; i++){
            System.out.print(strArray[i]);
        }
    }
} import java.util.Scanner; Scanner java.util public class Main {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        int K = sc.nextInt();

        String S = sc.next();
        
        String[] strArray = S.split("");
        strArray[K-1] = strArray[K-1].toLowerCase();

        for(int i=0; i < strArray.length; i++){
            System.out.print(strArray[i]);
        }
    }
} Main public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        int K = sc.nextInt();

        String S = sc.next();
        
        String[] strArray = S.split("");
        strArray[K-1] = strArray[K-1].toLowerCase();

        for(int i=0; i < strArray.length; i++){
            System.out.print(strArray[i]);
        }
    } main {

        Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        int K = sc.nextInt();

        String S = sc.next();
        
        String[] strArray = S.split("");
        strArray[K-1] = strArray[K-1].toLowerCase();

        for(int i=0; i < strArray.length; i++){
            System.out.print(strArray[i]);
        }
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int N = sc.nextInt(); N sc.nextInt() sc.nextInt sc int K = sc.nextInt(); K sc.nextInt() sc.nextInt sc String S = sc.next(); S sc.next() sc.next sc String[] strArray = S.split(""); strArray S.split("") S.split S "" strArray[K-1] = strArray[K-1].toLowerCase() strArray[K-1] strArray K-1 K 1 strArray[K-1].toLowerCase() strArray[K-1].toLowerCase strArray[K-1] strArray K-1 K 1 for(int i=0; i < strArray.length; i++){
            System.out.print(strArray[i]);
        } int i=0; int i=0; i 0 i < strArray.length i strArray.length strArray strArray.length i++ i++ i {
            System.out.print(strArray[i]);
        } {
            System.out.print(strArray[i]);
        } System.out.print(strArray[i]) System.out.print System.out System System.out strArray[i] strArray i String[] args args public class Main {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        int K = sc.nextInt();

        String S = sc.next();
        
        String[] strArray = S.split("");
        strArray[K-1] = strArray[K-1].toLowerCase();

        for(int i=0; i < strArray.length; i++){
            System.out.print(strArray[i]);
        }
    }
} public class Main {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        int K = sc.nextInt();

        String S = sc.next();
        
        String[] strArray = S.split("");
        strArray[K-1] = strArray[K-1].toLowerCase();

        for(int i=0; i < strArray.length; i++){
            System.out.print(strArray[i]);
        }
    }
} Main
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        int K = sc.nextInt();

        String S = sc.next();
        
        String[] strArray = S.split("");
        strArray[K-1] = strArray[K-1].toLowerCase();

        for(int i=0; i < strArray.length; i++){
            System.out.print(strArray[i]);
        }
    }
}