public class LinkedList {
    private Node head;
    private int size = 0;
    private class Node {
        T data;
        Node next;
        Node(T data) {
            this.data = data;
            this.next = null;
        }
    }

    public void insertAtHead(T data) {
        Node newNode = new Node<>(data);
        newNode.next = head;
        head = newNode;
        size++;
    }

    public void insertAtTail(T data) {
        Node newNode = new Node<>(data);
        if (head == null) {
            insertAtHead(data);
            return;
        }
        Node current = head;
        while (current.next != null) {
            current = current.next;
        }
        current.next = newNode;
        size++;
    }

    public void insertAtIndex(int index, T data) {
        if (index < 0 || index > size) {
            return;
        }
        if (index == 0) {
            insertAtHead(data);
            return;
        }
        Node newNode = new Node<>(data);
        Node current = head;
        for (int i = 0; i < index - 1; i++) {
            current = current.next;
        }
        newNode.next = current.next;
        current.next = newNode;
        size++;
    }

    public boolean delete(T data) {
        if (head == null) {
            return false;
        }
        if (head.data.equals(data)) {
            head = head.next;
            size--;
            return true;
        }
        Node current = head;
        while (current.next != null) {
            if (current.next.data.equals(data)) {
                current.next = current.next.next;
                size--;
                return true;
            }
            current = current.next;
        }
        return false;
    }

    public int search(T data) {
        Node current = head;
        int index = 0;
        while (current != null) {
            if (current.data.equals(data)) {
                return index;
            }
            current = current.next;
            index++;
        }
        return -1;
    }

    public int size() {
        return size;
    }
}