Compilare: user.cpp: In function ‘void dfs(int, int)’: user.cpp:22:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<V[nod].size();i++) ^ user.cpp: In function ‘int main()’: user.cpp:58:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=1;i<=E.size();i++) ^ user.cpp:63:43: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=1;j<=(E.size()-(1<<i))+1;j++) ^ user.cpp:47:32: 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:48:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&q); ^ user.cpp:51:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&x); ^ user.cpp:75:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&a,&b); ^