Compilare: user.cpp: In function ‘void df(int)’: user.cpp:21:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<g[x].size();++i){ ^ user.cpp: In function ‘void df(int, int)’: user.cpp:31:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<g[x].size();++i){ ^ user.cpp: In function ‘int main()’: user.cpp:62:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<ret.size();++i){ ^ user.cpp:78:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<ret.size();++i){ ^