public class Node<T>
{
    public T Data;
    public Node<T> Next;

    public Node(T data)
    {
        Data = data;
        Next = null;
    }
}

public class QueueLinkedList<T>
{
    private Node<T> front, rear;

    public QueueLinkedList()
    {
        front = rear = null;
    }

    public void Enqueue(T item)
    {
        var newNode = new Node<T>(item);
        if (rear == null)
        {
            front = rear = newNode;
            return;
        }
        rear.Next = newNode;
        rear = newNode;
    }

    public T Dequeue()
    {
        if (front == null)
            throw new InvalidOperationException("Queue is empty.");

        var data = front.Data;
        front = front.Next;

        if (front == null)
            rear = null;

        return data;
    }
}

public class QuickSortExample
{
    public void QuickSort(int[] arr, int low, int high)
    {
        if (low < high)
        {
            int pi = Partition(arr, low, high);

            QuickSort(arr, low, pi - 1);
            QuickSort(arr, pi + 1, high);
        }
    }

    private int Partition(int[] arr, int low, int high)
    {
        int pivot = arr[high];
        int i = (low - 1);

        for (int j = low; j < high; j++)
        {
            if (arr[j] < pivot)
            {
                i++;
                (arr[i], arr[j]) = (arr[j], arr[i]);
            }
        }

        (arr[i + 1], arr[high]) = (arr[high], arr[i + 1]);
        return i + 1;
    }
}

public class AVLNode
{
    public int Key;
    public AVLNode Left, Right;
    public int Height;

    public AVLNode(int key)
    {
        Key = key;
        Height = 1;
    }
}

public class AVLTree
{
    private AVLNode root;

    int Height(AVLNode node) => node?.Height ?? 0;

    int BalanceFactor(AVLNode node) => Height(node.Left) - Height(node.Right);

    AVLNode RightRotate(AVLNode y)
    {
        var x = y.Left;
        var T2 = x.Right;

        x.Right = y;
        y.Left = T2;

        y.Height = Math.Max(Height(y.Left), Height(y.Right)) + 1;
        x.Height = Math.Max(Height(x.Left), Height(x.Right)) + 1;

        return x;
    }

    AVLNode LeftRotate(AVLNode x)
    {
        var y = x.Right;
        var T2 = y.Left;

        y.Left = x;
        x.Right = T2;

        x.Height = Math.Max(Height(x.Left), Height(x.Right)) + 1;
        y.Height = Math.Max(Height(y.Left), Height(y.Right)) + 1;

        return y;
    }

    public AVLNode Insert(AVLNode node, int key)
    {
        if (node == null)
            return new AVLNode(key);

        if (key < node.Key)
            node.Left = Insert(node.Left, key);
        else if (key > node.Key)
            node.Right = Insert(node.Right, key);
        else
            return node;

        node.Height = 1 + Math.Max(Height(node.Left), Height(node.Right));

        int balance = BalanceFactor(node);

        if (balance > 1 && key < node.Left.Key)
            return RightRotate(node);

        if (balance < -1 && key > node.Right.Key)
            return LeftRotate(node);

        if (balance > 1 && key > node.Left.Key)
        {
            node.Left = LeftRotate(node.Left);
            return RightRotate(node);
        }

        if (balance < -1 && key < node.Right.Key)
        {
            node.Right = RightRotate(node.Right);
            return LeftRotate(node);
        }

        return node;
    }
}

import hashlib
import json

class Block:
    def __init__(self, index, transactions, previous_hash):
        self.index = index
        self.transactions = transactions
        self.previous_hash = previous_hash
        self.nonce = 0
        self.hash = self.calculate_hash()

    def calculate_hash(self):
        block_string = json.dumps({
            'index': self.index,
            'transactions': self.transactions,
            'previous_hash': self.previous_hash,
            'nonce': self.nonce
        }, sort_keys=True).encode()
        return hashlib.sha256(block_string).hexdigest()

# Пример использования
block = Block(1, ['tx1', 'tx2'], '0000abc123')
print(block.hash)