public static int NhapN(){
int n = int.Parse(Console.ReadLine());
public static int[] NhapMang(int n) {
for (int i = 0; i < n; i++) {
arr[i] = int.Parse(Console.ReadLine());
public static bool KiemTraChuSoLe(int a) {
public static int Tong(int[] arr) {
for (int i = 0; i < arr.Length; i++) {
if (KiemTraChuSoLe(arr[i])) {
public static void Main()