import java.util.Scanner;
import java.util.InputMismatchException;

class Main {
   public static void main(String args[]) {
      int x=0 ,y=0;
      int sum = 0;
      String s;
      Scanner scanner = new Scanner(System.in);
      x = scanner.nextInt();
      y = scanner.nextInt();
      s = scanner.next();
      scanner.close();

      String s1 = null;
      if (y-1>-1) {
         s1 = s.substring(0,y-1);
      }
      char s4 = s.charAt(y-1);
      String s3 = null;
      if (y<s.length()) {
         s3 = s.substring(y,s.length());
      }
      String s2 = String.valueOf(s4);
      s2 = s2.toLowerCase();
      if (s1 != null && s3 != null) {
         System.out.println(s1 + s2 + s3);
      } else if (s1 != null) {
         System.out.println(s1 + s2);
      } else if (s3 != null) {
         System.out.println(s2 + s3);
      } else{
         System.out.println(s2);
      }
   }
} import java.util.Scanner; Scanner java.util import java.util.InputMismatchException; InputMismatchException java.util class Main {
   public static void main(String args[]) {
      int x=0 ,y=0;
      int sum = 0;
      String s;
      Scanner scanner = new Scanner(System.in);
      x = scanner.nextInt();
      y = scanner.nextInt();
      s = scanner.next();
      scanner.close();

      String s1 = null;
      if (y-1>-1) {
         s1 = s.substring(0,y-1);
      }
      char s4 = s.charAt(y-1);
      String s3 = null;
      if (y<s.length()) {
         s3 = s.substring(y,s.length());
      }
      String s2 = String.valueOf(s4);
      s2 = s2.toLowerCase();
      if (s1 != null && s3 != null) {
         System.out.println(s1 + s2 + s3);
      } else if (s1 != null) {
         System.out.println(s1 + s2);
      } else if (s3 != null) {
         System.out.println(s2 + s3);
      } else{
         System.out.println(s2);
      }
   }
} Main public static void main(String args[]) {
      int x=0 ,y=0;
      int sum = 0;
      String s;
      Scanner scanner = new Scanner(System.in);
      x = scanner.nextInt();
      y = scanner.nextInt();
      s = scanner.next();
      scanner.close();

      String s1 = null;
      if (y-1>-1) {
         s1 = s.substring(0,y-1);
      }
      char s4 = s.charAt(y-1);
      String s3 = null;
      if (y<s.length()) {
         s3 = s.substring(y,s.length());
      }
      String s2 = String.valueOf(s4);
      s2 = s2.toLowerCase();
      if (s1 != null && s3 != null) {
         System.out.println(s1 + s2 + s3);
      } else if (s1 != null) {
         System.out.println(s1 + s2);
      } else if (s3 != null) {
         System.out.println(s2 + s3);
      } else{
         System.out.println(s2);
      }
   } main {
      int x=0 ,y=0;
      int sum = 0;
      String s;
      Scanner scanner = new Scanner(System.in);
      x = scanner.nextInt();
      y = scanner.nextInt();
      s = scanner.next();
      scanner.close();

      String s1 = null;
      if (y-1>-1) {
         s1 = s.substring(0,y-1);
      }
      char s4 = s.charAt(y-1);
      String s3 = null;
      if (y<s.length()) {
         s3 = s.substring(y,s.length());
      }
      String s2 = String.valueOf(s4);
      s2 = s2.toLowerCase();
      if (s1 != null && s3 != null) {
         System.out.println(s1 + s2 + s3);
      } else if (s1 != null) {
         System.out.println(s1 + s2);
      } else if (s3 != null) {
         System.out.println(s2 + s3);
      } else{
         System.out.println(s2);
      }
   } int x=0 x 0 y=0; y 0 int sum = 0; sum 0 String s; s Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) x = scanner.nextInt() x scanner.nextInt() scanner.nextInt scanner y = scanner.nextInt() y scanner.nextInt() scanner.nextInt scanner s = scanner.next() s scanner.next() scanner.next scanner scanner.close() scanner.close scanner String s1 = null; s1 null if (y-1>-1) {
         s1 = s.substring(0,y-1);
      } y-1>-1 y-1 y 1 -1 1 {
         s1 = s.substring(0,y-1);
      } s1 = s.substring(0,y-1) s1 s.substring(0,y-1) s.substring s 0 y-1 y 1 char s4 = s.charAt(y-1); s4 s.charAt(y-1) s.charAt s y-1 y 1 String s3 = null; s3 null if (y<s.length()) {
         s3 = s.substring(y,s.length());
      } y<s.length() y s.length() s.length s {
         s3 = s.substring(y,s.length());
      } s3 = s.substring(y,s.length()) s3 s.substring(y,s.length()) s.substring s y s.length() s.length s String s2 = String.valueOf(s4); s2 String.valueOf(s4) String.valueOf String s4 s2 = s2.toLowerCase() s2 s2.toLowerCase() s2.toLowerCase s2 if (s1 != null && s3 != null) {
         System.out.println(s1 + s2 + s3);
      } else if (s1 != null) {
         System.out.println(s1 + s2);
      } else if (s3 != null) {
         System.out.println(s2 + s3);
      } else{
         System.out.println(s2);
      } s1 != null && s3 != null s1 != null s1 null s3 != null s3 null {
         System.out.println(s1 + s2 + s3);
      } System.out.println(s1 + s2 + s3) System.out.println System.out System System.out s1 + s2 + s3 s1 + s2 + s3 s1 s2 s3 if (s1 != null) {
         System.out.println(s1 + s2);
      } else if (s3 != null) {
         System.out.println(s2 + s3);
      } else{
         System.out.println(s2);
      } s1 != null s1 null {
         System.out.println(s1 + s2);
      } System.out.println(s1 + s2) System.out.println System.out System System.out s1 + s2 s1 s2 if (s3 != null) {
         System.out.println(s2 + s3);
      } else{
         System.out.println(s2);
      } s3 != null s3 null {
         System.out.println(s2 + s3);
      } System.out.println(s2 + s3) System.out.println System.out System System.out s2 + s3 s2 s3 {
         System.out.println(s2);
      } System.out.println(s2) System.out.println System.out System System.out s2 String args[] args
import java.util.Scanner;
import java.util.InputMismatchException;

class Main {
   public static void main(String args[]) {
      int x=0 ,y=0;
      int sum = 0;
      String s;
      Scanner scanner = new Scanner(System.in);
      x = scanner.nextInt();
      y = scanner.nextInt();
      s = scanner.next();
      scanner.close();

      String s1 = null;
      if (y-1>-1) {
         s1 = s.substring(0,y-1);
      }
      char s4 = s.charAt(y-1);
      String s3 = null;
      if (y<s.length()) {
         s3 = s.substring(y,s.length());
      }
      String s2 = String.valueOf(s4);
      s2 = s2.toLowerCase();
      if (s1 != null && s3 != null) {
         System.out.println(s1 + s2 + s3);
      } else if (s1 != null) {
         System.out.println(s1 + s2);
      } else if (s3 != null) {
         System.out.println(s2 + s3);
      } else{
         System.out.println(s2);
      }
   }
}
