#include<cstdio>
#include<vector>
using namespace std;
long n,d,k,i;
long a[1000001];
long c[1000001];
long ind[1000001];
long f[125000001];
void read () {
	long i;
	//unsigned long B,b;
	//vector <long> v;
	scanf("%ld%ld%ld",&d,&n,&k);
	for (i=1;i<=n;i++) {
		scanf("%ld",&a[i]);
		/*if (a[i]-a[(*(v.begin()))]<=d)
			ind[i]=*(v.begin());
		else
			while (!v.empty()) {
				v.erase(v.begin(),v.begin()+1);
				if (a[i]-a[(*(v.begin()))]<=d) {
					ind[i]=*(v.begin());
					break;
				}
			}
		v.push_back(i);*/
	/*	B=a[i]>>3;
		b=a[i]&7;
		f[B]=f[B]|(1u<<3);
		ind[i]=d-a[i]-1;
		B=*/
	}
}

long cautbin (long st , long dr ,long val) {
	long m,i;
	i=dr;
	while (st<=dr) {
		m=(st+dr)>>1;
		if (a[m]==val)
			return c[m];
		if (a[m]<val)
			st=m+1;
		else
			dr=m-1;
	}
	return c[st];
}

void rez() {
	long i,rasengan,rasengan2,min_rasengan2,j,st,dr,val,m;
	for (i=1;i<=n;i++) {
		rasengan=c[i-1]+1;
		st=0;
		dr=i;
		val=a[i]-d;
		j=-1;
		if (val>=0) {
			while (st<=dr) {
				m=(st+dr)>>1;
				if (a[m]==val) {
					j=m;
					break;
				}
				if (a[m]<val)
					st=m+1;
				else
					dr=m-1;
			}
		}
		if (j==-1)
			j=st;
		min_rasengan2=c[j]+k;
		if (rasengan<min_rasengan2)
			c[i]=rasengan;
		else
			c[i]=min_rasengan2;
	}
	printf("%ld\n",c[n]);
}

int main () {

	freopen("zombie.in","r",stdin);
	freopen("zombie.out","w",stdout);
	
	read();
	rez();
	return 0;
}