title: operator< overload for std::map's int type comparison? (I want it to sort in descending order..)
body: <p>I have encountered a problem that I want to define a map, that is sorted internally by the first's descending order. if the first is not a primary type, like if it's a class, I can just overload the "&lt;" within that class, but I don't know how to deal with the int type. Any suggestion?</p>
  
  <p>Thanks a lot!!</p>