# include <stdio.h>   
FILE *f=fopen("ciur.in","r"),*g=fopen("ciur.out","w");
char P[200005];
int A[2000], i,j,d,N;

int main()
{
   fscanf(f,"%d",&N);
   fclose(f);
   for (i=1;i<=N;i++)
	P[i]=1;
   d=0;
   for (i=2;i<= N;i++)
	if (P[i])
	{
	   d++;
	   for (j=i+i; j<=N; j+=i)
		P[j] = 0;
	}
    j=0;
    for (i=N;i>1;i--){
      if (P[i]) { j++;
		  A[j]=i;
		  if (j==1000)
		  break;
		}
      }
   fprintf(g,"%d\n", d);
   for (i=j;i>0;i--)
      fprintf(g,"%d ",A[i]);
  fclose(g);
  return 0;   
}