Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:36:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(st.size() == n) cerr << "mlc\n"; ^ user.cpp: In function ‘int main()’: user.cpp:46:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("fenrir.in", "r", stdin); ^ user.cpp:47:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("fenrir.out", "w", stdout); ^