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

using namespace std;

typedef long long LL;
typedef set<LL> LLSet;

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);
	LLSet y;
	LL ans = (T * 2 + 1) * N;
	for (LL i = 0; i < N; ++i) {
		LL x;
		sb >> x;
		for (LL z : y) {
			LL a = min(x, z);
			LL b = max(x, z);
			LL c = ((a % D) + D) % D;
			LL d = ((b % D) + D) % D;
			if (c == d) {
				LL am = a + T * D;
				LL bn = b - T * D;
				if (am >= bn) {
					ans -= (am - bn + D) / D;
				}
			}
		}
		y.insert(x);
	}
	cout << ans << endl;
	return 0;
}