public static int GetDecimalsCount(decimal[] arrayToSearch, decimal[][] ranges)
        {
            // #5. Implement the method using "do..while" statements.
            if (arrayToSearch is null)
            {
                throw new ArgumentNullException(nameof(arrayToSearch));
            }

            if (ranges is null)
            {
                throw new ArgumentNullException(nameof(ranges));
            }

            for (int i = 0; i < ranges.Length; i++)
            {
                if (ranges[i] is null)
                {
                    throw new ArgumentNullException(nameof(ranges));
                }
            }

            for (int i = 0; i < ranges.Length; i++)
            {
                if (ranges[i].Length != 2)
                {
                    throw new ArgumentException("Lenght of range must be 2", nameof(ranges));
                }
            }

            int j = 0;

            for (int i = 0; i < arrayToSearch.Length; i++)
            {
                for (int k = 0; k < ranges.Length; k++)
                {
                    if (arrayToSearch[i] >= ranges[k][0] && arrayToSearch[i] <= ranges[k][1])
                    {
                        j++;
                        break;
                    }
                }
            }

            return j;
        }