using System;

class Program
{
    public static void Main(string[] args)
    {
        var firstline = Console.ReadLine().Split(' ');
        var n = long.Parse(firstline[0]);
        var d = long.Parse(firstline[1]);
        var t = long.Parse(firstline[2]);
        var secondline = Console.ReadLine().Split(' ');
        var points = new long[n];
        var counted = new bool[n];
        for (long i = 0; i < n; i++)
        {
            points[i] = long.Parse(secondline[i]);
        }
        long count = 0;
        for (long i = 0; i < n; i++)
        {
            if (counted[i])
            {
                continue;
            }
            counted[i] = true;
            count += 2*t + 1;
            for (long k = i + 1; k < n; k++)
            {
                if ((points[k] - points[i])%d != 0)
                {
                    continue;
                }
                var distance = Math.Abs(points[k] - points[i]) / d;
                if (distance > 2 * t)
                {
                    continue;
                }
                counted[k] = true;
                count += distance + Math.Max(0, distance - t);
            }
        }
        Console.WriteLine(count);
    }
}