triunghi5.cpp: In function `bool cmp(point, point)': triunghi5.cpp:19: warning: control reaches end of non-void function triunghi5.cpp: In function `std::vector<point, std::allocator<point> > convex_hull(std::vector<point, std::allocator<point> >&)': triunghi5.cpp:45: warning: comparison between signed and unsigned integer expressions triunghi5.cpp:49: warning: comparison between signed and unsigned integer expressions triunghi5.cpp: In function `double determine_maximum_area(int)': triunghi5.cpp:87: warning: comparison between signed and unsigned integer expressions