Compilare: user.cpp: In function ‘bool bf(int)’: user.cpp:30:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<v[start].size();i++) ~^~~~~~~~~~~~~~~~ user.cpp:44:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<v[i].size();j++) ~^~~~~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:69:10: warning: unused variable ‘ok’ [-Wunused-variable] bool ok=bf(ans); ^~