#include<stdio.h>
#include<string.h>
int n,i,l,j,s[1020];
char a[2000010];
int main()
{
 freopen("ciur.in","r",stdin);
 freopen("ciur.out","w",stdout);
 scanf("%ld",&n);
 memset(a,0,sizeof(a));
 for(i=2;i<=n;++i)
    if(a[i]==0)
      {++l;
       for(j=i*i;j<=n;j+=i) a[j]=1;
      }
 printf("%ld\n",l);
 for(i=0,j=n;((i<l)&&(i<1000)&&(j>1));--j) if(a[j]==0)s[++i]=j;
 for(;i;--i)printf("%ld ",s[i]);
 printf("\n");
 return 0;
}