So now we enter the first part of this journey – there’s plenty more coming – where altitude sickness is a looming enemy, so as a result we have developed a strategy long before the day we arrive in Cusco. Flying in from Puerto Maldonado adds to the risk, coming straight from low lying wetlands to a city at 3,400 metres in less than an hour gives no opportunity for graduation, just a steep learning curve in which a large dose of being sensible is called for. We’re not always good at being sensible. Consequently we hatch a plan. There’s a certain regime to follow for the first 48 hours…