import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        long d = sc.nextInt();
        long t = sc.nextInt();
        int BASE = 1000000000;
        long count = 0;
        HashMap<Long, Long> map = new HashMap<>();
        int[] arr = new int[n];
        for (int i = 0; i < n; i++) {
            arr[i] = sc.nextInt();
        }
        Arrays.sort(arr);
        for (int i = 0; i < n; i++) {
            long x = arr[i] + BASE;
            long mod = x % d;
            if (map.containsKey(mod)) {
                long y = map.get(mod);
                if (x - y > 2 * t * d) {
                    count += 2 * t + 1;
                } else {
                    count += (x - y) / d;
                }
            } else {
                count += 2 * t + 1;
            }
            map.put(mod, x);
        }
        System.out.println(count);
    }
}