Compilare: user.cpp: In function 'void dfs1(int)': user.cpp:17: warning: comparison between signed and unsigned integer expressions user.cpp: In function 'void dfs2(int, std::vector<int, std::allocator<int> >&)': user.cpp:27: warning: comparison between signed and unsigned integer expressions user.cpp: In function 'int main()': user.cpp:59: warning: comparison between signed and unsigned integer expressions user.cpp:60: warning: comparison between signed and unsigned integer expressions