prac 5 ex 2

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace prac_5_ex_2
{
    class Program
    {
        static int SumOfDividers(int a)
        {
            int s = 0;
            for (int i = 1; i <= Math.Sqrt(a); ++i)
                if (a % i == 0)
                {
                    if (a / i != i) s += i + a / i;
                    else s += i;
                }
            return s;
        }
        static bool IsPrime(int a)
        {
            int cnt = 0;
            for (int i = 1; i <= Math.Sqrt(a); ++i)
            {
                if (a % i == 0) cnt++;
            }
            if (cnt == 1) return true;
            else return false;
        }
        static void Main(string[] args)
        {
          //example
           /* Console.Write("Введите n: ");
            int n = int.Parse(Console.ReadLine());*/
          //a)
            /*Console.Write("a)\n\ta = ");
            int aa = int.Parse(Console.ReadLine());
            Console.Write("\tb = ");
            int ba = int.Parse(Console.ReadLine());
            for (int i = aa; i <= ba; i++)
                Console.WriteLine("\t{0} — {1}", i, SumOfDividers(i));*/

          //b)
            /*Console.Write("a)\n\ta = ");
            int ab = int.Parse(Console.ReadLine());
            Console.Write("\tb = ");
            int bb = int.Parse(Console.ReadLine());
            Console.Write("\tn = ");
            int n = int.Parse(Console.ReadLine());
            for (int i = ab; i <= bb; i++)
                if (SumOfDividers(i) == n) Console.WriteLine("\t{0}", i);*/

            //c)
            Console.Write("a)\n\ta = ");
            int ac = int.Parse(Console.ReadLine());
            Console.Write("\tb = ");
            int bc = int.Parse(Console.ReadLine());
            int max = 0;
            for (int i = bc; i > ac; i--)
                if (!IsPrime(bc)) max = SumOfDividers(ac);
            for (int i = ac+1; i <= bc; i++)
                if (SumOfDividers(i) == max) Console.WriteLine("\t{0}", i);

            Console.ReadKey();
        }
    }
}