Compilare: user.cpp: In function ‘void DFS(int, int)’: user.cpp:22:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < adj[node].size();i++) ^ user.cpp: In function ‘int main()’: user.cpp:48:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("lca.in", "r", stdin); ^ user.cpp:49:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("lca.out", "w", stdout); ^ user.cpp:51:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n, &m); ^ user.cpp:55:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &dad[i]); ^ user.cpp:64:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &a, &b); ^