import java.util.*;
public class Main {

    private static Node linkedlist1_FNode;
    private static Node linkedlist1_LNode = null;
    private static Node linkedlist2_FNode;
    private static Node linkedlist2_LNode = null;
    
    public static void main(String[] args) {
        // TODO code application logic here
        
        Scanner input = new Scanner(System.in);
        
        System.out.printf("Enter first string:");
        String str1 = input.next();
        
        System.out.printf("\nEnter second string:");
        String str2 = input.next();
        
        char[] ch1 = str1.toCharArray();
        char[] ch2 = str2.toCharArray();
        
        for(int i = 0; i < str1.length(); i++){
            create(ch1[i], 1);                      
        }
        for(int j = 0; j < str2.length(); j++){
            create(ch2[j], 2);                      
        }
        
        display(1);
        display(2);
        
        append();
        //subString();
        
    }
    
    public static void create(char ch, int linkedlist){     //inserts node into list
        if(linkedlist == 1){
            Node n1 = new Node(ch, null);    //create node
            if(linkedlist1_LNode != null){   //if it's not the first node
                linkedlist1_LNode.setNext(n1);
                linkedlist1_LNode = n1;
            }
            else{   //if n is the first node
                linkedlist1_FNode = n1;
                linkedlist1_LNode = n1;
            }
        }
        if(linkedlist == 2){
            Node n2 = new Node(ch, null);    //create node
            if(linkedlist2_LNode != null){   //if it's not the first node
                linkedlist2_LNode.setNext(n2);
                linkedlist2_LNode = n2;
            }
            else{   //if n is the first node
                linkedlist2_FNode = n2;
                linkedlist2_LNode = n2;
            }
        }
        
    }
    
    public static void display(int linkedlist){   //display all the data in the nodes
        if(linkedlist == 1){
            System.out.print("Linked list for first string: \n");
            Node n1 = linkedlist1_FNode;
            while(n1!=null){     //loops forward displaying nodes data
                System.out.print(n1.getWord()+ " --> ");
                n1 = n1.getNext();    //move to next node in the list
            }
            System.out.print("null");
        }
        
        if(linkedlist == 2){
            System.out.print("\nLinked list for second string: \n");
            Node n2 = linkedlist2_FNode;
            while(n2!=null){     //loops forward displaying nodes data
                System.out.print(n2.getWord()+ " --> ");
                n2 = n2.getNext();    //move to next node in the list
            }
            System.out.print("null");
        }
    }
    
    public static void append(){
        Node n2 = linkedlist2_FNode;
        char x;    
        while(n2!=null){ 
            x = n2.getWord(); //nodes data placed in a variable
            Node n1 = new Node(x, null);
            if(linkedlist1_LNode != null){   //if it's not the first node
                linkedlist1_LNode.setNext(n1); 
                linkedlist1_LNode = n1;    
            }
            n2 = n2.getNext();  //move to next node in the list
        }
        System.out.print("\nAppend : \n");
        display(1);
        //linkedlist2_FNode=null;
        //display(2);
    }   



public class Node{
    
    private char letter;
    private Node next; //reference to the next node
    
    public Node(char letter, Node next){ //constructor
        this.letter = letter;
        this.next = next;
    }
  
    public void setWord(char letter){
        this.letter = letter;
    }
    
    public char getWord(){
        return letter;
    }
    
    public void setNext(Node next){
        this.next = next;
    }
    
    public Node getNext(){
        return next;
    }
   
}