class MyLinkedList {

    Node head;
    int size = 0;

    static class Node {
        int val;
        Node next;

        public Node() {}
        public Node(int val) {
            this.val = val;
        }
        public Node(int val, Node next) {
            this.val = val;
            this.next = next;
        }
    }

    public MyLinkedList() {
        this.head = new Node();
        this.size = 0;
    }

    public int get(int index) {
        if(size == 0) return -1;
        int idx = 0;
        Node temp = head;
        while(temp != null) {
            if(idx == index) return temp.val;
            idx++;
            temp = temp.next;
        }
        // print();
        return -1;
    }

    public void addAtHead(int val) {
        if(size == 0) head.val = val;
        else{
            Node temp = head;
            head = new Node(val);
            head.next = temp;
        }
        size++;
        // print();
    }

    public void addAtTail(int val) {
        if(size == 0) {
            addAtHead(val);
            return;
        }
        Node newNode = new Node(val);
        Node temp = head;
        while(temp.next != null) {
            temp = temp.next;
        }
        temp.next = newNode;
        size++;
        // print();
    }

    public void addAtIndex(int index, int val) {
        if(index > 0 && size == 0) {
            return;
        }
        if(index == 0 || size == 0) {
            addAtHead(val);
            return;
        }
        if(index > size-1) {
            addAtTail(val);
            return;
        }
        Node newNode = new Node(val);
        Node temp = head;
        int idx = 0;
        while(temp != null && idx != index-1) {
            idx++;
            temp = temp.next;
        }

        if(temp == null) {
            addAtTail(val);
            return;
        }

        Node old = temp.next;
        temp.next = newNode;
        newNode.next = old;
        size++;
        // print();
    }

    public void deleteAtIndex(int index) {
        if(index > size-1) {
            return;
        }
        if(index == 0) {
            head = head.next;
            return;
        }
        int idx = 0;
        Node temp = head;
        while(temp != null && idx != index-1) {
            idx++;
            temp = temp.next;
        }

        if(temp != null && temp.next != null) temp.next = temp.next.next;
        size--;
        // print();
    }

    // public void print() {
    //     Node temp = head;
    //     while(temp != null) {
    //         System.out.print(temp.val + " ");
    //         temp = temp.next;
    //     }
    //     System.out.println("Size:" +  this.size);
    // }
}

/**
 * Your MyLinkedList object will be instantiated and called as such:
 * MyLinkedList obj = new MyLinkedList();
 * int param_1 = obj.get(index);
 * obj.addAtHead(val);
 * obj.addAtTail(val);
 * obj.addAtIndex(index,val);
 * obj.deleteAtIndex(index);
 */