[codes=c#]using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace th1
{
    class Program
    {
        static void c1()
        {
            Console.Write(“Nhap vao ho va ten: “);
            string hoten = Console.ReadLine();
            Console.Write(“Nhap vao tuoi: “);
            int tuoi = Convert.ToInt32(Console.ReadLine());
            Console.Write(“Nhap vao gioi tinh: “);
            string gioitinh = Console.ReadLine();
            Console.Write(“Nhap vao so thik: “);
            string sothik = Console.ReadLine();
            Console.WriteLine(“Ten la: ” + hoten + “\tTuoi la ” + tuoi + “\tGioi tinh la ” + gioitinh + “\tSo thik la ” + sothik);
            Console.ReadLine();
        }

        static void c2()
        {
            int ttc2 = 0;
            do
            {
                Console.WriteLine(“Nhap vao gia tri 1->7. 0 de thoat. (Mac dinh Chu nhat co gia tri 1) >”);
                int thu = Convert.ToInt32(Console.ReadLine());
                switch (thu)
                {
                    case 1: Console.WriteLine(“Chu nhat”); ttc2 = 1; break;
                    case 2: Console.WriteLine(“Thu 2”); ttc2 = 1; break;
                    case 3: Console.WriteLine(“Thu 3”); ttc2 = 1; break;
                    case 4: Console.WriteLine(“Thu 4”); ttc2 = 1; break;
                    case 5: Console.WriteLine(“Thu 5”); ttc2 = 1; break;
                    case 6: Console.WriteLine(“Thu 6”); ttc2 = 1; break;
                    case 7: Console.WriteLine(“Thu 7”); ttc2 = 1; break;
                    case 0: ttc2 = 0; break;
                    default: Console.WriteLine(“Ko tim thay”); ttc2 = 1; break;
                }
            } while (ttc2 == 1);
        }

        static int nt(int b)
        {
            if (b <= 2) return 0;
            for (int i = 2; i < b; i++)
                if (b % i == 0) return 0;
            return 1;
        }
        static void c3()
        {
            
            Console.WriteLine(“Nhap so phan tu”);
            int n=Convert.ToInt32(Console.ReadLine());
            int[]a=new int[n];
            for (int i = 0; i < n; i++)
            {
                Console.Write(” a[{0}]= “, i);
                a[i] = Convert.ToInt32(Console.ReadLine());
            }

            Console.WriteLine(“Mang vua nhap la:”);
            foreach(int i in a)
               Console.Write(” {0} “,i);

            Console.WriteLine(“\n”);
            int ck = 0;
            foreach (int i in a)
                if (nt(i) == 1)
                {
                    ck = 1;
                    Console.Write(“So nguyen to co trong mang la: “);
                    Console.Write(“{0} “, i);
                }
                 if (ck == 0)
                     Console.Write(“KO coa snt nao”);
        }

        static void Main(string[] args)
        {
            int t = 0;
            do
            {

                Console.WriteLine(“Chon 1 2 or 3, 0 de thoat:> “);
                int c = Convert.ToInt32(Console.ReadLine());
                switch (c)
                {
                    case 0: t = 0; break;
                    case 1: c1(); t = 1; break;
                    case 2: c2(); t = 1; break;
                    case 3: c3(); t = 1; break;
                    default: Console.WriteLine(“Chon lai: >”); t = 1; break;
                }
            } while (t == 1);
            
        }
    }
}
[/codes]