#include <cstdio>
FILE *f,*g;
int v[1000100];
int a[1000100];
int n,k,d,mn,i,j;

inline int mnn(int x,int y) {
if (x>y) return y;
return x;
}

int main() {
f=fopen("zombie.in","r");
g=fopen("zombie.out","w");

fscanf(f,"%d%d%d",&d,&n,&k);

v[0]=0;

for (j=1,i=1;i<=n;i++) {
	fscanf(f,"%d",&a[i]);
	if (i<=k) {
		v[i]=i;
		continue;
		}
	while (a[j]+d-1<a[i]) j++;
	v[i]=mnn(v[j-1]+k,v[i-1]+1);
	}


fprintf(g,"%d",v[n]);
fclose(g);
return 0;
}