Compilare: user.cpp: In member function ‘bool cmp::operator()(std::pair<double, double>, std::pair<double, double>)’: user.cpp:64:10: warning: unused variable ‘u1’ [-Wunused-variable] double u1 = atan2(p1.second , p1.first); //[-pi, pi] ^ user.cpp:65:10: warning: unused variable ‘u2’ [-Wunused-variable] double u2 = atan2(p2.second , p2.first); ^ user.cpp: In function ‘void solve()’: user.cpp:172:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0 ; i < points.size() - 1; ++i) { ^