#include <iostream>
#include <algorithm>
#include <sstream>
#include <set>

using namespace std;

typedef long long LL;
typedef pair<LL, LL> LLLL;
typedef set<LLLL> LLLLSet;

int main(int argc, char *argv[])
{
	LL N, D, T;
	string s;
	getline(cin, s);
	stringstream sa(s);
	sa >> N >> D >> T;
	getline(cin, s);
	stringstream sb(s);
	LLLLSet y;
	LL ans = (T * 2 + 1) * N;
	for (LL i = 0; i < N; ++i) {
		LL x;
		sb >> x;
		LL a = x - D * T, b = x + D * T;
		LL c = ((a % D) + D) % D;
		for (LLLL r : y) {
			LL d = r.first;
			LL e = r.second;
			LL f = ((d % D) + D) % D;
			if (c == f) {
				if (a >= d && a <= e) {
					ans -= (e - a + D) / D;
				} else if (b >= d && b <= e) {
					ans -= (d - b + D) / D;
				}
			}
		}
		y.insert(LLLL(a, b));
	}
	cout << ans << endl;
	return 0;
}