    import java.util.*;
     public class Main{
     public static void main(String args[]){
                
       Scanner sc = new Scanner(System.in);
            
       int a = sc.nextInt();
       int b = sc.nextInt();
       String x = sc.nextLine();
       String c = sc.nextLine();
                
       if(b == 1){
         System.out.println(c.substring(0,1).toLowerCase() + c.substring(1));
       }else if(b < a){
         System.out.println(c.substring(0,b-1) + c.substring(b-1,b).toLowerCase() + c.substring(b));
       }else{
         System.out.println(c.substring(0,b-1) + c.substring(b-1).toLowerCase());
       }
     }
    } import java.util.*; util.* java public class Main{
     public static void main(String args[]){
                
       Scanner sc = new Scanner(System.in);
            
       int a = sc.nextInt();
       int b = sc.nextInt();
       String x = sc.nextLine();
       String c = sc.nextLine();
                
       if(b == 1){
         System.out.println(c.substring(0,1).toLowerCase() + c.substring(1));
       }else if(b < a){
         System.out.println(c.substring(0,b-1) + c.substring(b-1,b).toLowerCase() + c.substring(b));
       }else{
         System.out.println(c.substring(0,b-1) + c.substring(b-1).toLowerCase());
       }
     }
    } Main public static void main(String args[]){
                
       Scanner sc = new Scanner(System.in);
            
       int a = sc.nextInt();
       int b = sc.nextInt();
       String x = sc.nextLine();
       String c = sc.nextLine();
                
       if(b == 1){
         System.out.println(c.substring(0,1).toLowerCase() + c.substring(1));
       }else if(b < a){
         System.out.println(c.substring(0,b-1) + c.substring(b-1,b).toLowerCase() + c.substring(b));
       }else{
         System.out.println(c.substring(0,b-1) + c.substring(b-1).toLowerCase());
       }
     } main {
                
       Scanner sc = new Scanner(System.in);
            
       int a = sc.nextInt();
       int b = sc.nextInt();
       String x = sc.nextLine();
       String c = sc.nextLine();
                
       if(b == 1){
         System.out.println(c.substring(0,1).toLowerCase() + c.substring(1));
       }else if(b < a){
         System.out.println(c.substring(0,b-1) + c.substring(b-1,b).toLowerCase() + c.substring(b));
       }else{
         System.out.println(c.substring(0,b-1) + c.substring(b-1).toLowerCase());
       }
     } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int a = sc.nextInt(); a sc.nextInt() sc.nextInt sc int b = sc.nextInt(); b sc.nextInt() sc.nextInt sc String x = sc.nextLine(); x sc.nextLine() sc.nextLine sc String c = sc.nextLine(); c sc.nextLine() sc.nextLine sc if(b == 1){
         System.out.println(c.substring(0,1).toLowerCase() + c.substring(1));
       }else if(b < a){
         System.out.println(c.substring(0,b-1) + c.substring(b-1,b).toLowerCase() + c.substring(b));
       }else{
         System.out.println(c.substring(0,b-1) + c.substring(b-1).toLowerCase());
       } b == 1 b 1 {
         System.out.println(c.substring(0,1).toLowerCase() + c.substring(1));
       } System.out.println(c.substring(0,1).toLowerCase() + c.substring(1)) System.out.println System.out System System.out c.substring(0,1).toLowerCase() + c.substring(1) c.substring(0,1).toLowerCase() c.substring(0,1).toLowerCase c.substring(0,1) c.substring c 0 1 c.substring(1) c.substring c 1 if(b < a){
         System.out.println(c.substring(0,b-1) + c.substring(b-1,b).toLowerCase() + c.substring(b));
       }else{
         System.out.println(c.substring(0,b-1) + c.substring(b-1).toLowerCase());
       } b < a b a {
         System.out.println(c.substring(0,b-1) + c.substring(b-1,b).toLowerCase() + c.substring(b));
       } System.out.println(c.substring(0,b-1) + c.substring(b-1,b).toLowerCase() + c.substring(b)) System.out.println System.out System System.out c.substring(0,b-1) + c.substring(b-1,b).toLowerCase() + c.substring(b) c.substring(0,b-1) + c.substring(b-1,b).toLowerCase() + c.substring(b) c.substring(0,b-1) c.substring c 0 b-1 b 1 c.substring(b-1,b).toLowerCase() c.substring(b-1,b).toLowerCase c.substring(b-1,b) c.substring c b-1 b 1 b c.substring(b) c.substring c b {
         System.out.println(c.substring(0,b-1) + c.substring(b-1).toLowerCase());
       } System.out.println(c.substring(0,b-1) + c.substring(b-1).toLowerCase()) System.out.println System.out System System.out c.substring(0,b-1) + c.substring(b-1).toLowerCase() c.substring(0,b-1) c.substring c 0 b-1 b 1 c.substring(b-1).toLowerCase() c.substring(b-1).toLowerCase c.substring(b-1) c.substring c b-1 b 1 String args[] args public class Main{
     public static void main(String args[]){
                
       Scanner sc = new Scanner(System.in);
            
       int a = sc.nextInt();
       int b = sc.nextInt();
       String x = sc.nextLine();
       String c = sc.nextLine();
                
       if(b == 1){
         System.out.println(c.substring(0,1).toLowerCase() + c.substring(1));
       }else if(b < a){
         System.out.println(c.substring(0,b-1) + c.substring(b-1,b).toLowerCase() + c.substring(b));
       }else{
         System.out.println(c.substring(0,b-1) + c.substring(b-1).toLowerCase());
       }
     }
    } public class Main{
     public static void main(String args[]){
                
       Scanner sc = new Scanner(System.in);
            
       int a = sc.nextInt();
       int b = sc.nextInt();
       String x = sc.nextLine();
       String c = sc.nextLine();
                
       if(b == 1){
         System.out.println(c.substring(0,1).toLowerCase() + c.substring(1));
       }else if(b < a){
         System.out.println(c.substring(0,b-1) + c.substring(b-1,b).toLowerCase() + c.substring(b));
       }else{
         System.out.println(c.substring(0,b-1) + c.substring(b-1).toLowerCase());
       }
     }
    } Main
    import java.util.*;
     public class Main{
     public static void main(String args[]){
                
       Scanner sc = new Scanner(System.in);
            
       int a = sc.nextInt();
       int b = sc.nextInt();
       String x = sc.nextLine();
       String c = sc.nextLine();
                
       if(b == 1){
         System.out.println(c.substring(0,1).toLowerCase() + c.substring(1));
       }else if(b < a){
         System.out.println(c.substring(0,b-1) + c.substring(b-1,b).toLowerCase() + c.substring(b));
       }else{
         System.out.println(c.substring(0,b-1) + c.substring(b-1).toLowerCase());
       }
     }
    }