12. Test Numbers

using System;

namespace _12._Test_Numbers
{
    class Program
    {
        static void Main(string[] args)
        {
            //Write a program, which finds all the possible combinations between two numbers – N and M.
            //The first digit decreases from N to 1, and the second digit increases from 1 to M. The two digits form a number. Multiply
            //the two digits, then multiply their product by 3. Add the result to the total sum.
            //You will also be given a third number, which will be the maximum boundary of the sum. If the sum is equal or greater than
            //this number you should stop the program. See the examples for further information.

            int n = int.Parse(Console.ReadLine());
            int m = int.Parse(Console.ReadLine());
            int maxSum = int.Parse(Console.ReadLine());

            int count = 0;
            int sum = 0;

            for (int i = n; i >= 1; i--)
            {
                for (int k = 1; k <= m; k++)
                {
                    sum += i * k * 3;
                    count++;
                    if (sum >= maxSum)
                    {
                        Console.WriteLine($"{count} combinations");
                        Console.WriteLine($"Sum: {sum} >= {maxSum}");
                        return;
                    }
                }
            }
            Console.WriteLine($"{count} combinations");
            Console.WriteLine($"Sum: {sum}");
            return;
        }
    }
}