Compilare: main.cpp: In function 'int main()': main.cpp:53:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<levels[i].size();j++) ~^~~~~~~~~~~~~~~~~ main.cpp:68:7: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(j==levels[i].size()&&ans!=-1) ~^~~~~~~~~~~~~~~~~~ main.cpp:79:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<vans.size();i++) ~^~~~~~~~~~~~