Compilare: user.cpp: In function ‘int main()’: user.cpp:44:26: warning: suggest parentheses around comparison in operand of ‘&’ [-Wparentheses] while (sol.size()>=2 & cp(sol[sol.size()-1],sol[sol.size()-2],a[i])>=0) sol.pop_back(); ^ user.cpp:50:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<sol.size();i++) cout<<sol[i].x<<' '<<sol[i].y<<'\n'; ^