using System;

​

public class Program

{

    public static void Main()

    {

        int maxNumberToEvaluate = 10000;

        int[] sumOfProperDivisors = new int[maxNumberToEvaluate + 1];

        int sumOfAllAmicableNumbers = 0;

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

        {

            for (int j = 1; j <= i / 2; j++)

            {

                if (i % j == 0)

                {

                    sumOfProperDivisors[i] += j;

                }

            }

        }

​

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

        {

            if (sumOfProperDivisors[i] <= maxNumberToEvaluate && i != sumOfProperDivisors[i] && i == sumOfProperDivisors[sumOfProperDivisors[i]])

            {

                sumOfAllAmicableNumbers += sumOfProperDivisors[i] + sumOfProperDivisors[sumOfProperDivisors[i]];

            }

        }

​

        sumOfAllAmicableNumbers = sumOfAllAmicableNumbers / 2;

        Console.WriteLine(sumOfAllAmicableNumbers);

    }

}