Eroare de compilare: user.cpp: In function ‘void dfs()’: user.cpp:20: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void dfs2()’: user.cpp:46: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:65: error: variable ‘std::ifstream f’ has initializer but incomplete type user.cpp:66: error: variable ‘std::ofstream g’ has initializer but incomplete type user.cpp:79: warning: suggest explicit braces to avoid ambiguous ‘else’