using System;

​

public class Program

{

    public static void Main()

    {

        int n;

        //nhapn(out n);

        Console.WriteLine("Bai tap Function");

        Console.WriteLine();

        Console.WriteLine("Vo Ngoc Minh Thu");

        Console.WriteLine();

        n = nhapsonguyen();

        //Console.Write("n={0}",n);

        /*Console.WriteLine("Cau 1: BCC cua {0}:",n);

        BCC(n);

        Console.WriteLine("Cau 2: Tong cac us cua {0} ={1}",n,tongus(n));

        Console.WriteLine("Cau 3: Co {0} so le <{1}",demle(n),n);

        Console.WriteLine("Cau 4: TBC cac so chan <={0} la {1}",n,TBCsole(n));

        */

        Console.WriteLine("n={0}", n);

        Console.WriteLine();

        Console.Write("Bai 1: ");

        chanle(n);

        Console.WriteLine();

        Console.Write("Bai 2: Cac so <n va la boi cua 3 va 5: ");

        bai2(n);

        Console.WriteLine();

        Console.WriteLine();

        Console.Write("Bai 3: Tong cac so trong khoang [1, n] = ");

        bai3(n);

        Console.WriteLine();

        Console.WriteLine();

        Console.Write("Bai 4: So cac chu so le cua n: ");

        demle(n);

        Console.WriteLine();

        Console.WriteLine();

        Console.Write("Bai 5: Trung binh cong cac so chan thuoc [1, n] = ");

        tongle(n);

    }

​

    static void nhapn(out int n)

    {

        do

        {

            Console.Write("Nhap n>0:");

            n = int.Parse(Console.ReadLine());

            if (n <= 0 || n > 999)

                Console.WriteLine("Sai, nhap lai...");

        }

        while (n <= 0 || n > 999);

    }

​

    static int nhapsonguyen()

    {

        int n;

        do

        {

            Console.Write("Nhap n>0:");

            n = int.Parse(Console.ReadLine());

            if (n <= 0 || n > 999)

                Console.WriteLine("Sai, nhap lai...");

        }

        while (n <= 0 || n > 999);

        return n;

    }

​

    //chanle

    static void chanle(int n)

    {

        if (n % 2 == 0)

        {

            Console.WriteLine("n la so chan");

        }

        else

        {

            Console.WriteLine("n la so le");

        }

    }

​

    //bai2: in ra cac so <n va la boi cua 3 va 5

    static int bai2(int n)

    {

        int so2 = 0;

        for (int i = 1; i < n; i++)

        {

            if (i % 3 == 0 && i % 5 == 0)

            {

                Console.Write(i + "; ");

            }

        }

​

        return so2;

    }

​

    //bai3: tinh tong cac so thuoc [1,n]

    static int bai3(int n)

    {

        int so3 = 0;

        for (int i = 1; i <= n; i++)

        {

            so3 = so3 + i;

        }

​

        Console.Write(so3);

        return so3;

    }

​

    //bai4: dem xem n co bao nhieu chu so le

    static int demle(int n)

    {

        int dem = 0, a, b, c;

        a = n / 100;

        b = (n % 100) / 10;

        c = n % 10;

        if (a % 2 != 0 && a != 0)

        {

            dem++;

        }

​

        if (b % 2 != 0 && b != 0)

        {

            dem++;

        }

​

        if (c % 2 != 0 && c != 0)

        {

            dem++;

        }

​

        Console.Write(dem);

        return dem;

    }

​

    //bai5: tinh trung binh cong cac so chan thuoc [1,n]

    static int tongle(int n)

    {

        int s = 0, c = 0;

        for (int i = 1; i <= n; i++)

        {

            if (i % 2 == 0)

            {

                c++;

                s += i;

            }

        }

​

        Console.Write(s / c);

        return s;

    }

​

    static float TBCsole(int n)

    {

        if (demle(n) == 0)

            return 0;

        return (float)tongle(n) / demle(n);

    }

}