using System;

public class Program

{

    public static void Main()

    {

        int N;

            int i;

            int st;

            Console.WriteLine("Nhap vao mot so: ");

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

            //BT1 - Xac dinh so nguyen to N

            i = 1;

            st = 0;

                while (i <= N)

                {

                    if (N % i == 0)

                    {

                    st = st + i;

                    }

                    i++;

                }

                if (st == N + 1)

                {

                    Console.WriteLine("{0} la so nguyen to",N);

                }

                else

                {

                    Console.WriteLine("{0} khong phai la so nguyen to",N);

                }

            //Liet ke - tinh tong cac so nguyen to nho hon N

            Console.WriteLine("Cac so nguyen to nho hon {0} la: ",N);

                int j;

                int s2;

                int t;

                int c;

                c = 0;

                t = 0;

                i = 1;            

                while (i < N)

                {

                    j = 1;

                    s2 = 0;

                    while (j <= i)

                    {

                        if(i%j==0)

                        {

                        s2 = s2 + j;

                        }

                        j++;

                    }

                    if(s2==i+1)

                    {

                        Console.WriteLine("{0}",i);

                        c++;

                        t = t + i;

                    }

                    i++;

                }

                Console.WriteLine("Co {0} so nguyen to nho hon {1}",c,N);

                Console.WriteLine("Tong cac so nguyen to nho hon {0} la {1}",N,t);

    }

}