prepare (1/3): 
finished

make (2/3): 
g++ -c main.cpp
main.cpp: In function 'int main(int, char**)':
main.cpp:440:22: warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]
  char* opt_strings = "vmptg:";
                      ^~~~~~~~
g++ -o main main.o
finished

clean (3/3): 
finished

all task finished, build successfully