public static int NhapN(string note) {
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 void XuatMang(int[] arr, int n) {
for (int i = 0; i < n; i++) {
Console.Write(arr[i] + " ");
public static void HoanVi(ref int a, ref int b) {
public static void XepTangDanSoAm(int[] arr, int n) {
for (int i = 0; i < n; i++) {
for (int j = i + 1; j < n; j++) {
if (arr[i] < 0 && arr[j] < 0 && arr[i] > arr[j]) {
HoanVi(ref arr[i], ref arr[j]);
public static void Main()
int n = NhapN("Nhap n: ");