Compilare: user.cpp: In function ‘int main()’: user.cpp:35:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1; i<c.size(); ++i) if(atan2(c[i].y,c[i].x)-atan2(c[i-1].y,c[i-1].x)>acos(-1)) ^ user.cpp:38:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<c.size(); ++i) g<<c[(i+st)%c.size()].z<<'\n'; ^