//Задача 1
Console.WriteLine("Введите год рождения: ");
int year1 = int.Parse(Console.ReadLine());

for (int year = 1900; year < 2000; year++)
{
    for (int month = 1; month <= 12; month++)
    {
        for (int day = 1; day <= DateTime.DaysInMonth(year, month); day++)
        {
            DateTime date = new DateTime(year, month, day);
            int age = year1 - year;
            int sum1 = CalculateSumOfSquares(year) - (day * day);

            if (sum1 == age)
            {
                Console.WriteLine("Дата рождения по свойству Васи: " + date.ToShortDateString());
            }
        }
    }
}

static int CalculateSumOfSquares(int year)
{
    int sum = 0;
    foreach (char c in year.ToString())
    {
        sum += int.Parse(c.ToString()) * int.Parse(c.ToString());
    }
    return sum;
}
//Задача 2
    Console.WriteLine("Введите буковки:");
    string originalString = Console.ReadLine();

    string packedString = PackString(originalString);
    Console.WriteLine("Packed String: " + packedString);
}

static string PackString(string originalString)
{
    if (string.IsNullOrEmpty(originalString))
    {
        return "";
    }

    string packed = "";
    int count = 1;

    for (int i = 0; i < originalString.Length; i++)
    {
        if (i == originalString.Length - 1 || originalString[i] != originalString[i + 1])
        {
            packed += count.ToString() + originalString[i];
            count = 1;
        }
        else
        {
            count++;
        }
    }

    return packed;
}
}

//Задача 3

Console.WriteLine("Введите цифры: ");
int secret = Convert.ToInt16(Console.ReadLine());
int guess = Convert.ToInt16(Console.ReadLine());

Console.WriteLine($"Быки: {CountBulls(secret, guess)}");
Console.WriteLine($"Коровы: {CountCows(secret, guess)}");

static int CountBulls(int secret, int guess)
{
    return secret.ToString().Zip(guess.ToString(), (s, g) => s == g ? 1 : 0).Sum();
}

static int CountCows(int secret, int guess)
{
    return secret.ToString().Intersect(guess.ToString()).Count() - CountBulls(secret, guess);
}