Compilare: user.cpp: In function ‘void bf(int, int)’: user.cpp:16:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<a[actual].size();i++) ^ user.cpp: In function ‘int bf2(int)’: user.cpp:29:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<a[actual].size();i++) ^ user.cpp: In function ‘void backt(int, int)’: user.cpp:37:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<a[nod].size();i++) ^