Compilare: main.cpp: In member function 'void convex_hull::calculate()': main.cpp:34:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v.size();i++) ~^~~~~~~~~ main.cpp:39:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v.size();i++) ~^~~~~~~~~ main.cpp: In member function 'int convex_hull::get_mn()': main.cpp:64:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(l+1<st.size()&&det(st[l+1],A,B)<0LL) return 1; ~~~^~~~~~~~~~ main.cpp:65:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(l+2<st.size()&&det(st[l+2],A,B)<0LL) return 1; ~~~^~~~~~~~~~ main.cpp:66:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(l+3<st.size()&&det(st[l+3],A,B)<0LL) return 1; ~~~^~~~~~~~~~ main.cpp:53:13: warning: unused variable 'lim' [-Wunused-variable] int lim=lg[st.size()]; ^~~ main.cpp: In function 'void build(int, int, int)': main.cpp:81:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<ch[2*nod].st.size();i++) ~^~~~~~~~~~~~~~~~~~~~ main.cpp:83:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<ch[2*nod+1].st.size();i++) ~^~~~~~~~~~~~~~~~~~~~~~