Compilare: main.cpp: In function 'int32_t main()': main.cpp:62:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(upper.size()>=d && cross(v[i],upper[upper.size()-2],upper[upper.size()-1])>=0){ ~~~~~~~~~~~~^~~ main.cpp:72:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<upper.size();i++){ ~^~~~~~~~~~~~~