How to accept only Russian from the form?

Question

ASP.NET

How in asp.net to accept only the Russian language in the model (the form returns the last name)?

[DataType(DataType.Text)]
        [Required(ErrorMessage = "Не указана фамилия")]
        public string Surname { get; set; }

Answer 1

Regex.IsMatch("[А-Яа-я]", Surname);

Answer 2

Regex.IsMatch("^[А-ЯЁ]{1}[а-яё]+$", Surname);
In this format, we check both the correctness of the character set and the correctness of the entered surname - with a capital letter.