import java.util.*;

public class Main {
    static int BASE = 1000000000;
	public static void main (String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int d = sc.nextInt();
		long t = sc.nextInt();
		int[] point = new int[n];
		for (int i = 0; i < n; i++) {
		    point[i] = sc.nextInt() + BASE;
		}
		Arrays.sort(point);
		HashMap<Integer, ArrayList<Integer>> map = new HashMap<>();
		for (int x : point) {
		    if (!map.containsKey(x % d)) {
		        map.put(x % d, new ArrayList<>());
		    }
		    map.get(x % d).add(x / d);
		}
		long ans = 0;
		for (ArrayList<Integer> list : map.values()) {
		    ans += t * 2 + 1;
		    for (int i = 0; i < list.size() - 1; i++) {
		        ans += Math.min(list.get(i + 1) - list.get(i), t * 2);
		    }
 		}
		System.out.println(ans);
	}
}