using System;

public class Program

{

    public static void Main()

    {

        var a = "123";

​

        if(a.Length == 3 && a[0] == '1')

            Console.WriteLine("passed");

        var b = a switch

        {

            { Length: 3 } => "passed",

            _ => "error"

        };

        Console.WriteLine(b);

    }

}