using System;

public class Program

{

    public static void Main()

    {

        int product = 1;

        int i = 1;

        int n = 10;

        //#1 

        // while loop, first 10 

        while (i < n)

        {

            //Console.WriteLine("i = {0}, n = {1}, product = {2}", i, n, product);

            product *= i;

            i++;

        }

        Console.WriteLine("The product of the first {0} numbers is {1}", i, product);

        // while loop, first 20 

        product = 1;

        i = 1;

        n = 20;

        while (i < n)

        {

            //Console.WriteLine("i = {0}, n = {1}, product = {2}", i, n, product);

            product *= i;

            i++;

        }

        Console.WriteLine("The product of the first {0} numbers is {1}", i, product);

        // for loop, first 10 

        for (i = 1, product = 1, n = 10; i < n; i++)

        {

            product *= i; 

        }

        Console.WriteLine("The product of the first {0} numbers is {1}", i, product);

​

        // for loop, first 20 

        for (i = 1, product = 1, n = 20; i < n; i++)

        {

            product *= i; 

        }

        Console.WriteLine("The product of the first {0} numbers is {1}", i, product);

        //#2 

        int m;

        int sum_result = 0;

        for (m = 1777; m <= 2022; m += 1)

        {

            sum_result += m;

        }

        Console.WriteLine(sum_result);

    }

}