I'm just going to go off topic because I feel it important.
Luisca, you are not a light smoker. You have, as I do, an addiction to a drug that will kill you. I do not mean that it "may" cause you harm or "may" cause shortness of breath or, are you ready for this one, "may" cause impotence. Among all the other "mays", they are not maybes, there are absolute certainties in many combinations.
Please, please, please PLEASE! quit while you've a chance. I do not and I wish I had listened all those years ago.
In closing. All you smokers, please quit before your doctor tells you that with luck you will live another 5 years. Take the pain for a week, and it will hurt, but it hurts rather less than being told you'll be dead soon.
The day you stop learning is the day you should die.