---

using System;

class Program
{
    static void Main()
    {
        Console.Write("Введите слово: ");
        string word = Console.ReadLine().ToLower();

        int count = 0;

        for (int i = 0; i < word.Length - 1; i++)
        {
            if (word[i] == 'а' && word[i + 1] == 'б')
            {
                count++;
            }
        }

        Console.WriteLine("Количество вхождений «аб»: " + count);
    }
}using System;

class Program
{
    static void Main()
    {
        Console.Write("Введите текст: ");
        string text = Console.ReadLine();

        bool insideQuotes = false;
        string result = "";

        foreach (char c in text)
        {
            if (c == '«')
            {
                insideQuotes = true;
            }
            else if (c == '»')
            {
                insideQuotes = false;
            }
            else if (!insideQuotes)
            {
                result += c;
            }
        }

        Console.WriteLine("Результат:");
        Console.WriteLine(result);
    }
}using System;

class Program
{
    static void Main()
    {
        string a = Console.ReadLine();
        string b = Console.ReadLine();
        string c = Console.ReadLine();

        foreach (string word in a.Split(' '))
            if (b.Contains(word) && c.Contains(word))
            {
                Console.WriteLine(word);
                break;
            }
    }
}