import java.util.Scanner;
public class Main{
 public static void main(String[] args){
   Scanner sc = new Scanner(System.in);
   int length1 = sc.nextInt();
   int b = sc.nextInt();
   String ccc = sc.next();
   
if(b ==1){
 String c1 = ccc.substring(0,1);
 String c2 = ccc.substring(1,length1);
  
  String cs = c1.toLowerCase();
  String cans1 = cs+c2;
  
  System.out.println(cans1);
}
   
else  if(b == length1){
 String c1 = ccc.substring(0,b-1);
 String c2 = ccc.substring(b-1,b);
  
  String cs = c2.toLowerCase();
  
  String cans2 = c1+cs;
  
  System.out.println(cans2);
}
   
 else{
  String c1 = ccc.substring(0,b-1);
 String c2 = ccc.substring(b-1,b);
  String c3 = ccc.substring(b,length1);
  
  String cs = c2.toLowerCase();
  
  String cans3 = c1+cs+c3;
  
  System.out.println(cans3);
}  
   
 }
} import java.util.Scanner; Scanner java.util public class Main{
 public static void main(String[] args){
   Scanner sc = new Scanner(System.in);
   int length1 = sc.nextInt();
   int b = sc.nextInt();
   String ccc = sc.next();
   
if(b ==1){
 String c1 = ccc.substring(0,1);
 String c2 = ccc.substring(1,length1);
  
  String cs = c1.toLowerCase();
  String cans1 = cs+c2;
  
  System.out.println(cans1);
}
   
else  if(b == length1){
 String c1 = ccc.substring(0,b-1);
 String c2 = ccc.substring(b-1,b);
  
  String cs = c2.toLowerCase();
  
  String cans2 = c1+cs;
  
  System.out.println(cans2);
}
   
 else{
  String c1 = ccc.substring(0,b-1);
 String c2 = ccc.substring(b-1,b);
  String c3 = ccc.substring(b,length1);
  
  String cs = c2.toLowerCase();
  
  String cans3 = c1+cs+c3;
  
  System.out.println(cans3);
}  
   
 }
} Main public static void main(String[] args){
   Scanner sc = new Scanner(System.in);
   int length1 = sc.nextInt();
   int b = sc.nextInt();
   String ccc = sc.next();
   
if(b ==1){
 String c1 = ccc.substring(0,1);
 String c2 = ccc.substring(1,length1);
  
  String cs = c1.toLowerCase();
  String cans1 = cs+c2;
  
  System.out.println(cans1);
}
   
else  if(b == length1){
 String c1 = ccc.substring(0,b-1);
 String c2 = ccc.substring(b-1,b);
  
  String cs = c2.toLowerCase();
  
  String cans2 = c1+cs;
  
  System.out.println(cans2);
}
   
 else{
  String c1 = ccc.substring(0,b-1);
 String c2 = ccc.substring(b-1,b);
  String c3 = ccc.substring(b,length1);
  
  String cs = c2.toLowerCase();
  
  String cans3 = c1+cs+c3;
  
  System.out.println(cans3);
}  
   
 } main {
   Scanner sc = new Scanner(System.in);
   int length1 = sc.nextInt();
   int b = sc.nextInt();
   String ccc = sc.next();
   
if(b ==1){
 String c1 = ccc.substring(0,1);
 String c2 = ccc.substring(1,length1);
  
  String cs = c1.toLowerCase();
  String cans1 = cs+c2;
  
  System.out.println(cans1);
}
   
else  if(b == length1){
 String c1 = ccc.substring(0,b-1);
 String c2 = ccc.substring(b-1,b);
  
  String cs = c2.toLowerCase();
  
  String cans2 = c1+cs;
  
  System.out.println(cans2);
}
   
 else{
  String c1 = ccc.substring(0,b-1);
 String c2 = ccc.substring(b-1,b);
  String c3 = ccc.substring(b,length1);
  
  String cs = c2.toLowerCase();
  
  String cans3 = c1+cs+c3;
  
  System.out.println(cans3);
}  
   
 } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int length1 = sc.nextInt(); length1 sc.nextInt() sc.nextInt sc int b = sc.nextInt(); b sc.nextInt() sc.nextInt sc String ccc = sc.next(); ccc sc.next() sc.next sc if(b ==1){
 String c1 = ccc.substring(0,1);
 String c2 = ccc.substring(1,length1);
  
  String cs = c1.toLowerCase();
  String cans1 = cs+c2;
  
  System.out.println(cans1);
}
   
else  if(b == length1){
 String c1 = ccc.substring(0,b-1);
 String c2 = ccc.substring(b-1,b);
  
  String cs = c2.toLowerCase();
  
  String cans2 = c1+cs;
  
  System.out.println(cans2);
}
   
 else{
  String c1 = ccc.substring(0,b-1);
 String c2 = ccc.substring(b-1,b);
  String c3 = ccc.substring(b,length1);
  
  String cs = c2.toLowerCase();
  
  String cans3 = c1+cs+c3;
  
  System.out.println(cans3);
} b ==1 b 1 {
 String c1 = ccc.substring(0,1);
 String c2 = ccc.substring(1,length1);
  
  String cs = c1.toLowerCase();
  String cans1 = cs+c2;
  
  System.out.println(cans1);
} String c1 = ccc.substring(0,1); c1 ccc.substring(0,1) ccc.substring ccc 0 1 String c2 = ccc.substring(1,length1); c2 ccc.substring(1,length1) ccc.substring ccc 1 length1 String cs = c1.toLowerCase(); cs c1.toLowerCase() c1.toLowerCase c1 String cans1 = cs+c2; cans1 cs+c2 cs c2 System.out.println(cans1) System.out.println System.out System System.out cans1 if(b == length1){
 String c1 = ccc.substring(0,b-1);
 String c2 = ccc.substring(b-1,b);
  
  String cs = c2.toLowerCase();
  
  String cans2 = c1+cs;
  
  System.out.println(cans2);
}
   
 else{
  String c1 = ccc.substring(0,b-1);
 String c2 = ccc.substring(b-1,b);
  String c3 = ccc.substring(b,length1);
  
  String cs = c2.toLowerCase();
  
  String cans3 = c1+cs+c3;
  
  System.out.println(cans3);
} b == length1 b length1 {
 String c1 = ccc.substring(0,b-1);
 String c2 = ccc.substring(b-1,b);
  
  String cs = c2.toLowerCase();
  
  String cans2 = c1+cs;
  
  System.out.println(cans2);
} String c1 = ccc.substring(0,b-1); c1 ccc.substring(0,b-1) ccc.substring ccc 0 b-1 b 1 String c2 = ccc.substring(b-1,b); c2 ccc.substring(b-1,b) ccc.substring ccc b-1 b 1 b String cs = c2.toLowerCase(); cs c2.toLowerCase() c2.toLowerCase c2 String cans2 = c1+cs; cans2 c1+cs c1 cs System.out.println(cans2) System.out.println System.out System System.out cans2 {
  String c1 = ccc.substring(0,b-1);
 String c2 = ccc.substring(b-1,b);
  String c3 = ccc.substring(b,length1);
  
  String cs = c2.toLowerCase();
  
  String cans3 = c1+cs+c3;
  
  System.out.println(cans3);
} String c1 = ccc.substring(0,b-1); c1 ccc.substring(0,b-1) ccc.substring ccc 0 b-1 b 1 String c2 = ccc.substring(b-1,b); c2 ccc.substring(b-1,b) ccc.substring ccc b-1 b 1 b String c3 = ccc.substring(b,length1); c3 ccc.substring(b,length1) ccc.substring ccc b length1 String cs = c2.toLowerCase(); cs c2.toLowerCase() c2.toLowerCase c2 String cans3 = c1+cs+c3; cans3 c1+cs+c3 c1+cs+c3 c1 cs c3 System.out.println(cans3) System.out.println System.out System System.out cans3 String[] args args public class Main{
 public static void main(String[] args){
   Scanner sc = new Scanner(System.in);
   int length1 = sc.nextInt();
   int b = sc.nextInt();
   String ccc = sc.next();
   
if(b ==1){
 String c1 = ccc.substring(0,1);
 String c2 = ccc.substring(1,length1);
  
  String cs = c1.toLowerCase();
  String cans1 = cs+c2;
  
  System.out.println(cans1);
}
   
else  if(b == length1){
 String c1 = ccc.substring(0,b-1);
 String c2 = ccc.substring(b-1,b);
  
  String cs = c2.toLowerCase();
  
  String cans2 = c1+cs;
  
  System.out.println(cans2);
}
   
 else{
  String c1 = ccc.substring(0,b-1);
 String c2 = ccc.substring(b-1,b);
  String c3 = ccc.substring(b,length1);
  
  String cs = c2.toLowerCase();
  
  String cans3 = c1+cs+c3;
  
  System.out.println(cans3);
}  
   
 }
} public class Main{
 public static void main(String[] args){
   Scanner sc = new Scanner(System.in);
   int length1 = sc.nextInt();
   int b = sc.nextInt();
   String ccc = sc.next();
   
if(b ==1){
 String c1 = ccc.substring(0,1);
 String c2 = ccc.substring(1,length1);
  
  String cs = c1.toLowerCase();
  String cans1 = cs+c2;
  
  System.out.println(cans1);
}
   
else  if(b == length1){
 String c1 = ccc.substring(0,b-1);
 String c2 = ccc.substring(b-1,b);
  
  String cs = c2.toLowerCase();
  
  String cans2 = c1+cs;
  
  System.out.println(cans2);
}
   
 else{
  String c1 = ccc.substring(0,b-1);
 String c2 = ccc.substring(b-1,b);
  String c3 = ccc.substring(b,length1);
  
  String cs = c2.toLowerCase();
  
  String cans3 = c1+cs+c3;
  
  System.out.println(cans3);
}  
   
 }
} Main
import java.util.Scanner;
public class Main{
 public static void main(String[] args){
   Scanner sc = new Scanner(System.in);
   int length1 = sc.nextInt();
   int b = sc.nextInt();
   String ccc = sc.next();
   
if(b ==1){
 String c1 = ccc.substring(0,1);
 String c2 = ccc.substring(1,length1);
  
  String cs = c1.toLowerCase();
  String cans1 = cs+c2;
  
  System.out.println(cans1);
}
   
else  if(b == length1){
 String c1 = ccc.substring(0,b-1);
 String c2 = ccc.substring(b-1,b);
  
  String cs = c2.toLowerCase();
  
  String cans2 = c1+cs;
  
  System.out.println(cans2);
}
   
 else{
  String c1 = ccc.substring(0,b-1);
 String c2 = ccc.substring(b-1,b);
  String c3 = ccc.substring(b,length1);
  
  String cs = c2.toLowerCase();
  
  String cans3 = c1+cs+c3;
  
  System.out.println(cans3);
}  
   
 }
}