Compilare: user.cpp: In function ‘std::pair<std::__cxx11::basic_string<char>, std::__cxx11::basic_string<char> > prevnext(std::__cxx11::string)’: user.cpp:25:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(count(s.begin(),s.end(),'0')==s.size()/2*2) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~ user.cpp:25:7: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] if(count(s.begin(),s.end(),'0')==s.size()/2*2) ^ user.cpp:29:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(count(s.begin(),s.end(),'1')==s.size()) nxt=-1; ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~