using System;

internal class Range
{
    internal int[] this[int n]
    {
        get { return this[0, n]; }
    }

    internal int[] this[int a, int b]
    {
        get { return this[a, b, 1]; }
    }

    internal int[] this[int a, int b, int step]
    {
        get
        {
            if (a < b && step > 0)
            {
                int len = (b - a + (step - 1)) / step;
                int[] arr = new int[len];
                int val = a;
                for (int i = 0; i < len; i++, val += step)
                {
                    arr[i] = val;
                }
                return arr;
            }
            else if (a > b && step < 0)
            {
                int tmp = a;
                a = b;
                b = tmp;
                int abStep = Math.Abs(step);
                int len = (b - a + (abStep - 1)) / abStep;
                int[] arr = new int[len];
                int val = b;
                for (int i = 0; i < len; i++, val += step)
                {
                    arr[i] = val;
                }
                return arr;
            }
            else if (a == b && step != 0)
            {
                return new int[0];
            }
            throw new ArgumentException();
        }
    }
}