Just as an update of sorts regarding altitude sickness. A headache that can be relieved by medication is a mild form of altitude sickness. However, should your headache not be reduced with medication (mate de cocoa is of dubious value IMO), you become sick to your stomach, become disoriented or confused, or breathing is extremely difficult, then you need to head to a lower altitude fast to acclimate to the altitude. Do not head to higher ground until the sypmtoms have subsided. I have known of a couple of very fit people who have had severe cases - one almost died and needed helicopter evacuation. Again treat AMS with the respect it deserves.