#include<fstream.h>
#define nmax 2000001
char nr[nmax];
long long i,n,j,x[1002],p=0,k=0;
int main(){
ifstream f("ciur.in");
ofstream g("ciur.out");

f>>n;
for(i=2;i<=n;i++)	  nr[i]=1;
for(i=2;i<=n;i++)
      if(nr[i]!=0)
	 {k++;
	 for(j=i+i;j<=n;j+=i)
	      nr[j]=0;
	 }
for(i=n;i>1;i--)
	{if(nr[i]==1)
		x[p++]=i;
	if(p==1000)	 break; }
g<<k<<"\n";
for(i=p-1;i>0;i--)
	g<<x[i]<<" ";
g<<x[i];
return 0;
}