Compilare: user.cpp: In function ‘std::vector<PTX> make_hull(std::vector<PTX>)’: user.cpp:31:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < ptr.size(); ++i) { ^ user.cpp:37:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < ue.size(); ++i) ^ user.cpp: In function ‘int main()’: user.cpp:48:21: warning: unused variable ‘cd’ [-Wunused-variable] int n, a, b, c, cd; ^