Compilare: main.cpp: In function 'std::vector<point> hull(std::vector<point>)': main.cpp:26:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0,p=1;i>=0;i+=(p=i==(v.size()-1)?-p:p)){ ~^~~~~~~~~~~~~~ main.cpp: In function 'double getarea(std::vector<point>)': main.cpp:36:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<v.size();++i){ ~^~~~~~~~~