Compilare: user.cpp: In function ‘void dfs(int, int, int)’: user.cpp:9:107: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] void dfs(int nod,int n1,int lev){niv[nod]=lev;tata[nod]=n1;if(lev%h==0){n1=nod;}for(int j=0;j<v[nod].size();j++){dfs(v[nod][j],n1,lev+1);}} ^ user.cpp: In function ‘int main()’: user.cpp:12:29: 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:13:31: 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:14:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&n,&m); ^ user.cpp:15:41: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(int i=2;i<=n;i++){scanf("%d",&a[i]);v[a[i]].push_back(i);} ^ user.cpp:16:55: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] dfs(1,0,0);for(int i=1;i<=m;i++){scanf("%d %d",&x,&y);printf("%d\n",lca(x,y));} ^