#include<cstdio>
int n,d,k,i,j,a,v[1001000],x[1001000];
FILE *f,*g;
int minim(int a,int b){
    if(a<b)
        return a;
    return b;
}
int main(){
    f=fopen("zombie.in","r");
    g=fopen("zombie.out","w");
    fscanf(f,"%d%d%d",&d,&n,&k);
    j=1;
    for(i=1;i<=n;i++){
        fscanf(f,"%d",&v[i]);
        while(j<=i&&v[i]-v[j]>=d){
            j++;
        }
        x[i]=minim(x[i-1]+1,x[j-1]+k);
    }
    fprintf(g,"%d",x[n]);



    fclose(f);
    fclose(g);
    return 0;
}