import java util NoSuchElementExcepti on public class DLL private clas

import java.util.NoSuchElementException;

public class DLL {
    private class Cell {
        private Integer value;
        private Cell next;
        private Cell prev;
        private Cell begin;
        private Cell end;

        public Cell(Integer value) {
            this.value = value;
            next = null;
            prev = null;
            begin = null;
            end = null;
        }

        public void setBegin(Cell begin) {
            this.begin = begin;
        }

        public void setEnd(Cell end) {
            this.end = end;
        }

        public Integer getValue() {
            return value;
        }

        public Cell getNext() {
            return next;
        }

        public Cell getPrev() {
            return prev;
        }

        public void setValue(Integer value) {
            this.value = value;
        }

        public void setNext(Cell next) {
            this.next = next;
        }

        public void setPrev(Cell prev) {
            this.prev = prev;
        }
    }

    private Cell begin;
    private Cell end;
    private int size;

    public DLL() {
        begin = null;
        end = null;
        size = 0;
    }

    private Cell getCell(int index) {
        if (index < 0 || index >= size) {
            throw new IndexOutOfBoundsException();
        } else if (isEmpty()) {
            throw new NoSuchElementException();
        }

        Cell cell = begin;
        int s = 0;
        while (s < index) {
            cell = cell.getNext();
            s++;
        }

        return cell;
    }

    public void add(int value) {
        if (isEmpty()) {
            Cell newCell = new Cell(value);
            begin = newCell;
            end = newCell;
            newCell.setBegin(newCell);
            newCell.setEnd(newCell);
        } else {
            Cell newCell = new Cell(value);
            end.setNext(newCell);
            newCell.setPrev(end);
            end.setBegin(null);
            end = newCell;
            newCell.setBegin(begin);
            begin.setEnd(newCell);
        }
        size++;
    }

    public int get(int index) {
        return getCell(index).getValue();
    }

    public int indexOf(int value) {
        int ans = -1;
        Cell cell = begin;
        int index = 0;

        while (cell != null) {
            if (cell.getValue() == value) {
                ans = index;
                break;
            }
            cell = cell.getNext();
            index++;
        }

        return ans;
    }

    public boolean isEmpty() {
        return size == 0;
    }

    public int remove(int index) {
        if (index < 0 || index >= size) {
            throw new IndexOutOfBoundsException();
        }

        int ans;
        Cell cell = getCell(index);
        ans = cell.getValue();
        Cell prev = cell.getPrev();
        Cell next = cell.getNext();
        prev.setNext(next);
        next.setPrev(prev);
        size--;

        return ans;
    }


    public void set(int index, int value) {
        Cell cell = getCell(index);
        cell.setValue(value);
    }
}