#include <algorithm>
#include <cstdlib>
#include <initializer_list>
#include <iostream>

using namespace std;

long long N, D, T;
long long X[100];

int main() {
	cin >> N >> D >> T;
	for (int i = 0; i < N; i++) {
		cin >> X[i];
	}
	long long res = N * (1 + 2 * T);
	for (int i = 0; i < N; i++) {
		long long mi0 = X[i] - D * T, ma0 = X[i] + D * T;
		for (int j = i + 1; j < N; j++) {
			if (X[i] % D != X[j] % D || abs(X[i] - X[j]) > 2 * D * T) {
				continue;
			}
			long long mi = min(mi0, X[j] - D * T), ma = max(ma0, X[j] + D * T);
			res -= 2 * (1 + 2 * T) - ((ma - mi) / D + 1);
		}
	}
	cout << res << endl;
	return 0;
}