void mycontract::transfer(eosio::name const & from, eosio::name const & to, eosio::asset const & quantity, std::string const & memo)
{
  if(to != get_self()) return;
  // Process the transfer
}

void mycontract::transfer(eosio::name const & from, eosio::name const & to, eosio::asset const & quantity, std::string const & memo)
{
  if(get_first_receiver() != eosio::name("eosio.token")) return;
}