prepare (1/3): 
finished

make (2/3): 
g++ -c Hw2.cpp
Hw2.cpp: In function 'int det_sel(int*, int, int, int)':
Hw2.cpp:38:14: error: 'ceil' was not declared in this scope
  int Csize = ceil(sizeof(A) / 5);
              ^~~~
Hw2.cpp:79:24: error: 'floor' was not declared in this scope
  pivot = det_sel(C, 0, floor(n / 5), ceil(n / 10));
                        ^~~~~
Hw2.cpp:79:24: note: suggested alternative: 'float'
  pivot = det_sel(C, 0, floor(n / 5), ceil(n / 10));
                        ^~~~~
                        float
Makefile:7: recipe for target 'main.o' failed
make: *** [main.o] Error 1

build failed