import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int num1 = sc.nextInt();
        int num2 = sc.nextInt();
        String str = sc.next();
        
        String str1 = str.substring(0,num2 - 1);
        String str2 = str.substring(num2 - 1, num2);
        String str3 = str.substring(num2);

        System.out.println(str1 + str2.toLowerCase() + str3);
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int num1 = sc.nextInt();
        int num2 = sc.nextInt();
        String str = sc.next();
        
        String str1 = str.substring(0,num2 - 1);
        String str2 = str.substring(num2 - 1, num2);
        String str3 = str.substring(num2);

        System.out.println(str1 + str2.toLowerCase() + str3);
    }
} Main public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int num1 = sc.nextInt();
        int num2 = sc.nextInt();
        String str = sc.next();
        
        String str1 = str.substring(0,num2 - 1);
        String str2 = str.substring(num2 - 1, num2);
        String str3 = str.substring(num2);

        System.out.println(str1 + str2.toLowerCase() + str3);
    } main {
        Scanner sc = new Scanner(System.in);
        int num1 = sc.nextInt();
        int num2 = sc.nextInt();
        String str = sc.next();
        
        String str1 = str.substring(0,num2 - 1);
        String str2 = str.substring(num2 - 1, num2);
        String str3 = str.substring(num2);

        System.out.println(str1 + str2.toLowerCase() + str3);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int num1 = sc.nextInt(); num1 sc.nextInt() sc.nextInt sc int num2 = sc.nextInt(); num2 sc.nextInt() sc.nextInt sc String str = sc.next(); str sc.next() sc.next sc String str1 = str.substring(0,num2 - 1); str1 str.substring(0,num2 - 1) str.substring str 0 num2 - 1 num2 1 String str2 = str.substring(num2 - 1, num2); str2 str.substring(num2 - 1, num2) str.substring str num2 - 1 num2 1 num2 String str3 = str.substring(num2); str3 str.substring(num2) str.substring str num2 System.out.println(str1 + str2.toLowerCase() + str3) System.out.println System.out System System.out str1 + str2.toLowerCase() + str3 str1 + str2.toLowerCase() + str3 str1 str2.toLowerCase() str2.toLowerCase str2 str3 String[] args args public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int num1 = sc.nextInt();
        int num2 = sc.nextInt();
        String str = sc.next();
        
        String str1 = str.substring(0,num2 - 1);
        String str2 = str.substring(num2 - 1, num2);
        String str3 = str.substring(num2);

        System.out.println(str1 + str2.toLowerCase() + str3);
    }
} public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int num1 = sc.nextInt();
        int num2 = sc.nextInt();
        String str = sc.next();
        
        String str1 = str.substring(0,num2 - 1);
        String str2 = str.substring(num2 - 1, num2);
        String str3 = str.substring(num2);

        System.out.println(str1 + str2.toLowerCase() + str3);
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int num1 = sc.nextInt();
        int num2 = sc.nextInt();
        String str = sc.next();
        
        String str1 = str.substring(0,num2 - 1);
        String str2 = str.substring(num2 - 1, num2);
        String str3 = str.substring(num2);

        System.out.println(str1 + str2.toLowerCase() + str3);
    }
}