#include<fstream>

using namespace std;
ifstream in("zombie.in");
ofstream out("zombie.out");
int d,n,k,v[1000001],D[1000001],cost;

int main(){
	int i,last;
	in>>d>>n>>k;
	last=-k+1;
	if(k==1){
		cost=n;
		goto finish;
	}
	for(i=1;i<=n;++i){
		in>>v[i];
		if(v[i]-(last+k)<=d)
			D[i]=1;
		else
			D[i]=k;
		if(v[i]-d>last+k)
			last=v[i];
	}
	for(i=1;i<=n;++i)
		if(D[i]>D[i-1])
			cost+=D[i];
	finish:
	out<<cost;
	return 0;
}