using System;
public class Program
{
public static void Main()
Console.Write("n = ");
int n = int.Parse(Console.ReadLine());
int i = n - 1;
int sum = 0;
while (i > 0) {
if (n % i == 0) {
sum += i;
}
if (sum > n) {
Console.WriteLine("{0} is not a perfect number", n);
return;
--i;
if (sum == n) {
Console.WriteLine("{0} is a perfect number", n);
else {
