#include<stdio.h>

#define maxn 1000005

FILE*f=fopen("zombie.in","r");
FILE*g=fopen("zombie.out","w");

int d,n,k,i,pmin,st,x,L,p,m,u;
int D[maxn],Poz[maxn],H[maxn],v[maxn];

inline void swap ( int &a , int &b ){
	int aux = a; a = b; b = aux;
}

inline void urca(int poz){
	while ( poz != 0 && D[ H[poz/2] ] > D[ H[poz] ] ){
		swap(H[poz],H[poz/2]);
		swap(Poz[H[poz]],Poz[H[poz/2]]);
		poz = poz >> 1;
	}
}

inline void coboara(int x){
	int y = 0;
	
	while ( x != y ){
		y = x;
		if ( (y << 1) <= L && D[H[ y << 1 ]] < D[H[ x ]] )
			x = y << 1;
		if ( (y << 1) + 1 <= L && D[H[(y<<1)+1]] < D[H[ x ]] )
			x = ( y << 1 ) + 1;
		swap(H[x],H[y]);
		swap(Poz[H[x]],Poz[H[y]]);
	}
}

inline void insert_heap ( int x) {
	H[++L] = x; Poz[x] = L;
	urca(L);
}

inline void erase_first () {
	swap(H[1],H[L]); swap(Poz[H[1]],Poz[H[L]]); H[L] = 0; Poz[H[L]] = -1;
	--L; coboara(1);
}

inline int cb ( int val ){
	p = 1; u = i-1;
	
	while ( p <= u ){
		m = p + (u - p) / 2;
		if ( v[m] >= val )
			u = m - 1;
		else
			p = m + 1;
	}
	return p;
}

int main () {
	
	fscanf(f,"%d %d %d",&d,&n,&k); st = -k + 1;
	
	for ( i = 1 ; i <= n ; ++i ){
		++st; if ( st > 0 )	insert_heap(st);
		fscanf(f,"%d",&x); v[i] = x;
		D[i] = D[i-1] + 1;
		pmin = cb(x-d);
		while ( H[1] < pmin && L ){
			erase_first();
		}
		if ( D[i] > D[H[1]-1] + k ){
			D[i] = D[H[1]-1] + k;
		}
	}
	
	fprintf(g,"%d\n",D[n]);
	
	fclose(f);
	fclose(g);
	
	return 0;
}