Compilare: user.cpp: In function ‘int main()’: user.cpp:9:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] int main(){freopen("lca.in","r",stdin);freopen("lca.out","w",stdout);scanf("%d %d",&n,&m);for(int i=2;i<=n;i++){scanf("%d",&a[i]);v[a[i]].push_back(i);}dfs(1,0,0);for(int i=1;i<=m;i++){scanf("%d %d",&x,&y);printf("%d\n",lca(x,y));}} ^ user.cpp:9:69: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] int main(){freopen("lca.in","r",stdin);freopen("lca.out","w",stdout);scanf("%d %d",&n,&m);for(int i=2;i<=n;i++){scanf("%d",&a[i]);v[a[i]].push_back(i);}dfs(1,0,0);for(int i=1;i<=m;i++){scanf("%d %d",&x,&y);printf("%d\n",lca(x,y));}} ^ user.cpp:9:90: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] int main(){freopen("lca.in","r",stdin);freopen("lca.out","w",stdout);scanf("%d %d",&n,&m);for(int i=2;i<=n;i++){scanf("%d",&a[i]);v[a[i]].push_back(i);}dfs(1,0,0);for(int i=1;i<=m;i++){scanf("%d %d",&x,&y);printf("%d\n",lca(x,y));}} ^ user.cpp:9:130: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] int main(){freopen("lca.in","r",stdin);freopen("lca.out","w",stdout);scanf("%d %d",&n,&m);for(int i=2;i<=n;i++){scanf("%d",&a[i]);v[a[i]].push_back(i);}dfs(1,0,0);for(int i=1;i<=m;i++){scanf("%d %d",&x,&y);printf("%d\n",lca(x,y));}} ^ user.cpp:9:206: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] int main(){freopen("lca.in","r",stdin);freopen("lca.out","w",stdout);scanf("%d %d",&n,&m);for(int i=2;i<=n;i++){scanf("%d",&a[i]);v[a[i]].push_back(i);}dfs(1,0,0);for(int i=1;i<=m;i++){scanf("%d %d",&x,&y);printf("%d\n",lca(x,y));}} ^