prepare (1/3): 
finished

make (2/3): 
g++ -O2 -std=c++11 -o main.o -c main.cpp 
g++ -O2 -std=c++11 -o orderbook.o -c orderbook.cpp 
g++ -O2 -std=c++11 -o main main.o orderbook.o
finished

clean (3/3): 
finished

all task finished, build successfully