using System;

using static System.Console;

using System.Globalization;

public class Program {

    public static void Main() {

        if (!ValidaData("24/10/2016")) { WriteLine("invalido"); }

        if (!ValidaHora("27:10:15")) { WriteLine("invalido"); }

    }

    public static bool ValidaData(string maskdata) {

        return DateTime.ParseExact(maskdata, "dd/MM/yyyy", CultureInfo.InvariantCulture) <= DateTime.Now.AddDays(-1);

    }

​

    public static bool ValidaHora(string maskhora) {

        return Int32.Parse(maskhora.Split(':')[0]) <= 24;

    }

}