Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:29:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0 ; i < v[nod].size(); i++) { ^ user.cpp: In function ‘void dfs2(int)’: user.cpp:52:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int k = 0; k < v [st.top()].size(); k++) { ^ user.cpp: In function ‘int main()’: user.cpp:138:7: warning: unused variable ‘first’ [-Wunused-variable] int first = 0; ^