import java.util.Scanner;
import java.util.Arrays; 
class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    sc.nextInt();
    int k = sc.nextInt();
    char[] letters = sc.next().toCharArray();
    letters[k-1] += 32;
    String output = String.valueOf(letters);
    System.out.println(output);
  }
} import java.util.Scanner; Scanner java.util import java.util.Arrays; Arrays java.util class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    sc.nextInt();
    int k = sc.nextInt();
    char[] letters = sc.next().toCharArray();
    letters[k-1] += 32;
    String output = String.valueOf(letters);
    System.out.println(output);
  }
} Main public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    sc.nextInt();
    int k = sc.nextInt();
    char[] letters = sc.next().toCharArray();
    letters[k-1] += 32;
    String output = String.valueOf(letters);
    System.out.println(output);
  } main {
    Scanner sc = new Scanner(System.in);
    sc.nextInt();
    int k = sc.nextInt();
    char[] letters = sc.next().toCharArray();
    letters[k-1] += 32;
    String output = String.valueOf(letters);
    System.out.println(output);
  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) sc.nextInt() sc.nextInt sc int k = sc.nextInt(); k sc.nextInt() sc.nextInt sc char[] letters = sc.next().toCharArray(); letters sc.next().toCharArray() sc.next().toCharArray sc.next() sc.next sc letters[k-1] += 32 letters[k-1] letters k-1 k 1 32 String output = String.valueOf(letters); output String.valueOf(letters) String.valueOf String letters System.out.println(output) System.out.println System.out System System.out output String[] args args
import java.util.Scanner;
import java.util.Arrays; 
class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    sc.nextInt();
    int k = sc.nextInt();
    char[] letters = sc.next().toCharArray();
    letters[k-1] += 32;
    String output = String.valueOf(letters);
    System.out.println(output);
  }
}