using System;

using System.Text.RegularExpressions; 

​

public class Program

{

    public static void Main()

    {

        Regex alphabetic = new Regex(@"^(.*[a-zA-Z]){3,}$");

        string x = "--783o %%$r/><u"; 

        if (!alphabetic.IsMatch(x))

            Console.WriteLine("True");

        else

            Console.WriteLine("False");

        //Console.WriteLine(y);

    }

}