You have to convert the value to integer, see:
using System;
                    
public class Program
{
    public static void Main()
    {
        int tempo = 0;
        
        if (int.TryParse(Console.ReadLine(), out tempo))            
            Console.WriteLine("O tempo {0} foi adicionado", tempo);            
        else 
            Console.WriteLine("Valor inteiro inválido");
    }
}
Entree:
10
Exit:
Time 10 has been added
The method TryParse does it for you.
See working on .NET Fiddle.
Editing
After clearing the AP’s doubt in chat I worked out this solution:
using System;
using System.Text.RegularExpressions;
                    
public class Program
{
    public static void Main()
    {
        Console.WriteLine("Comando: ");
        
        var comando = Console.ReadLine();
        
        if (VerrificarComando(comando))
        {
            var tempo = 0;
            
            if (int.TryParse(Regex.Match(comando, @"\d+").Value, out tempo))
            {
                Console.WriteLine("O tempo {0} foi adicionado", tempo);
                
                return;
            }
            
            Console.WriteLine("Valor inteiro inválido");
        }        
        
        Console.WriteLine("Comando inválido");
    }
    
    static bool VerrificarComando(string comando)
    {                    
        return Regex.Match(comando, @"\b(adicionartempo)\b").Success;
    }
}
See working on .NET Fiddle.
							
							
						 
Can it be in this format?: add time;(any number he has typed) In case the person would have to type add time; before typing the number
– user92401
@Betadarknight you want a function, like
AdicionarTempo()?– gato
No, the person would have to type add-time; before typing the number to be executed
– user92401
@Betadarknight as if it were some kind of option?
– gato
Yes, example: additiontime1;(time 1), additiontime2;(time 2) and so on
– user92401
@Betadarknight gives a look, I edited the answer.
– gato
Wouldn’t you be able to put everything together? When writing the add time already add time?
– user92401
But time is informed by the user or is a random value?
– gato
Informed by the user
– user92401
But that’s what the program does, the user enters the add-time command and then informs the time.
– gato
Let’s go continue this discussion in chat.
– user92401