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:36:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<v.size();++i){ ~^~~~~~~~~ main.cpp:39:13: warning: 'area' may be used uninitialized in this function [-Wmaybe-uninitialized] area+=cp({0, 0}, v[v.size()-1], v[0]); ~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~