Compilare: main.cpp: In function 'void dfs(int, int)': main.cpp:13:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < adj[u].size(); ++i) { ~~^~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:23:38: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("arbore4.in", "r", stdin); ^ main.cpp:24:40: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("arbore4.out", "w", stdout); ^