Жава норм работает

package com.Main;

import java.lang.*;
import java.util.Scanner;

class Main {
    static Node insert(Node head, int data) {
        Node current = head;
        Node newNode = new Node();
        newNode.data = data;
        if (head == null) {
            newNode.next = newNode;
            head = newNode;
        } else {
            while (current.next != head) {
                current = current.next;
            }
            newNode.next = head;
            current.next = newNode;
        }
        return head;
    }

    static void writeList(Node head) {
        Node current = head;
        if (findLength(head) == 1) {
            System.out.print("Номер последнего: " + head.data);
        } else {
            System.out.print("Список на данный момент: ");
            do {
                System.out.print(current.data + " ");
                current = current.next;
            } while (current != head);
            System.out.println();
        }
    }


    static int findLength(Node head) {
        Node current = head;
        int count = 0;
        if (head != null) {
            do {
                current = current.next;
                count++;
            } while (current != head);
        }
        return count;
    }

    static Node deleteFirst(Node head) {
        Node previous = head, next = head;
        while (previous.next != head) {
            previous = previous.next;
            next = previous.next;
        }
        System.out.println("Был удалён из круга номер " + head.data);
        previous.next = next.next;
        head = previous.next;
        return head;
    }

    static Node deleteAtPosition(Node head, int index, int length) {
        int count = 1;
        Node previous = head, next = head.next;
        if (index == 0) {
            head = deleteFirst(head);
            return head;
        } else {
            while (length > 0) {
                if (count == index) {
                    previous.next = next.next;
                    System.out.println("Был удалён из круга номер " + next.data);
                }
                previous = previous.next;
                next = previous.next;
                length--;
                count++;
            }
            return head;
        }
    }

    public static int findIndex(int length, int number) {
        int index = -1;
        int count = 0;
        length--;
        while (count != number) {
            index++;
            if (index > length) {
                index = 0;
            }
            count++;
        }
        return index;
    }

    public static void removeGuys(Node head, int length, int m) {
        while (length > 1) {
            int index = findIndex(length, m);
            head = deleteAtPosition(head, index, length);
            writeList(head);
            length--;
        }
    }

    public static int readNumber() {
        boolean isCorrect;
        int length = 0;
        Scanner in = new Scanner(System.in);
        do {
            isCorrect = false;
            try {
                length = in.nextInt();
                if (length < 2 || length > 10) {
                    System.out.println("Число должно быть больше единицы и меньше 11");
                    isCorrect = true;
                }
            } catch (Exception e) {
                System.out.println("Неверный ввод!");
                isCorrect = true;
                in.nextLine();
            }
        } while (isCorrect);
        return length;
    }

    public static Node fillList(Node head, int length) {
        length++;
        for (int i = 1; i < length; i++) {
            head = insert(head, i);
        }
        return head;
    }

    public static void writeTip(int number) {
        switch (number) {
            case 1:
                System.out.println("N ребят встали в круг. Каждый раз, начиная с первого, из круга выводится каждый M-й");
                break;
            case 2:
                System.out.println("Сколько человек находится в кругу?");
                break;
            case 3:
                System.out.println("Введите M");
                break;
        }
    }

    public static void main(String[] args) {
        writeTip(1);
        Node head = null;
        writeTip(2);
        int length = readNumber();
        writeTip(3);
        int m = readNumber();
        head = fillList(head, length);
        writeList(head);
        removeGuys(head, length, m);
    }
}