LL3remfirst.java

import java.io.*;
import java.util.*;

public class LL3remfirst {
  public static class Node {
    int data;
    Node next;
  }

  public static class LinkedList {
    Node head;
    Node tail;
    int size;

    void addLast(int val) {
      Node temp = new Node();
      temp.data = val;
      temp.next = null;

      if (size == 0) {
        head = tail = temp;
      } else {
        tail.next = temp;
        tail = temp;
      }

      size++;
    }

    public int size(){
      return size;
    }

    public void display(){
      for(Node temp = head; temp != null; temp = temp.next){
        System.out.print(temp.data + " ");
      }
      System.out.println();
    }

    public void removeFirst(){

        if(size==0){
            System.out.println("List is empty");
        }
        else if(size==1){
            head=tail=null;
            size--;

        }
        else{
            head = head.next;
            size--;
            

        }

     


    }
  }

  public static void main(String[] args) throws Exception {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    LinkedList list = new LinkedList();

    String str = br.readLine();
    while(str.equals("quit") == false){
      if(str.startsWith("addLast")){
        int val = Integer.parseInt(str.split(" ")[1]);
        list.addLast(val);
      } else if(str.startsWith("size")){
        System.out.println(list.size());
      } else if(str.startsWith("display")){
        list.display();
      } else if(str.startsWith("removeFirst")){
        list.removeFirst();
      }
      str = br.readLine();
    }
  }
}