prepare (1/3): 
finished

make (2/3): 
g++ -o main main.cpp unsorted_heap.h 
unsorted_heap.h:9:46: error: 'less' in namespace 'std' does not name a template type
 template<typename TYPE, typename COMP = std::less<TYPE> >
                                              ^~~~
unsorted_heap.h:9:50: error: expected '>' before '<' token
 template<typename TYPE, typename COMP = std::less<TYPE> >
                                                  ^
Makefile:2: recipe for target 'all' failed
make: *** [all] Error 1

build failed