#include <iostream>
#include <algorithm>
#include <cstdio>
#include <string>
#include <vector>
#include <set>

#define rep(x,to) for(int (x)=(0);(x)<(to);(x)++)

using namespace std;
typedef long long ll;


int main()
{
	
	ll N, D, T, res=0;
	cin >> N >> D >> T;
	vector<ll> X(N);
	rep(i,N) cin >> X[i];
	
	sort(X.begin(), X.end());
	vector<ll> am(N);
	set<ll> st;
	rep(i,N){
		am[i]=(X[i]+1000000000LL)%D;
		st.insert(am[i]);
	}
	
	for(auto x: st){
		ll oldmx=-1*1LL<<61;
		rep(i,N) if(x==am[i]){
			if(oldmx < X[i] -  D * T) res += 2*T+1;
			else res += (oldmx - (X[i] - D*T))/ D;
			oldmx = X[i] + D*T;
			//printf("%lld:%lld:%lld, ",res,X[i],oldmx);
		}
	}		
			
	
	cout << res << endl;
	return 0;
}