#include<cstdio>
#include<cstdlib>
#include<vector>
#include<queue>
#include<algorithm>


using namespace std;
using ll=long long;


priority_queue<pair<int,int> > que;


int min_u(int&m, int v)
{
	if(m==-1 || m>v)
	{
		m=v;
		return 1;
	}
	return 0;
}


void push(int t, int ct)
{
	if(t<=0) return;
	que.push(make_pair(-t, ct));
}


int pop(int& t, int& ct)
{
	if(que.empty()) return 0;
	t=-que.top().first;
	ct=que.top().second;
	que.pop();
	return 1;
}


void que_dump(void)
{
	auto q=que;
	printf("dump\n");
	for(;!q.empty();)
	{
		printf("t=%d ct=%d\n", -q.top().first, q.top().second);
		q.pop();
	}
	printf("\n");
}


ll solve(int n, int t)
{
	ll ans=n;
	ll inc=n*2;
	int ct=0, nt, nc;

	while(pop(nt, nc))
	{
		if(nt>t) break;
		ans+=inc*(nt-ct);
		inc--;
		if(nc) ans--;
		ct=nt;
	}
	ans+=inc*(t-ct);
	while(pop(nt, nc));
	return ans;
}


int main(void)
{
	vector<int> x;
	int n, d, t;
	int i, j, y, ay, c, cp_min, cp_min_t=0, cn_min;

	while(scanf("%d%d%d", &n ,&d, &t)==3)
	{
		x.resize(n);
		for(i=0;i<n;i++) scanf("%d", &x[i]);
		sort(x.begin(), x.end());
		for(i=n-1;i>0;i--)
		{
			if(x[i]==x[i-1]) x.erase(x.begin()+i);
		}
		n=x.size();

		for(i=0;i<n;i++)
		{
			cp_min=cn_min=-1;
			for(j=0;j<n;j++)
			{
				if(i==j) continue;

				y=x[i]-x[j];
				ay=abs(y);
				if(ay%d) continue;

				c=(ay+d)/(2*d);
				if(y<0)
				{
					if(min_u(cp_min, c))
					{
						cp_min_t=(ay%(2*d)==d);
					}
				}
				else
				{
					min_u(cn_min, c);
				}
			}
			push(cp_min, cp_min_t);
			push(cn_min, 1);
		}

		printf("%lld\n", solve(n, t));
	}
	return 0;
}