Compilare: user.cpp: In function ‘std::vector<int> Tree::dfs(int)’: user.cpp:31:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int p = 1; p < vec.size(); p++) ~~^~~~~~~~~~~~ user.cpp: In function ‘int Tree::solve(int)’: user.cpp:59:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int p = 1; p < vec.size(); p++) ~~^~~~~~~~~~~~