#include<stdio.h>
#define nmax 2000000
long long int i,j,k,n;
char v[nmax];

int main()
{
	freopen("ciur.in","r",stdin);
	freopen("ciur.out","w",stdout);

	scanf("%lld",&n);

	v[1]=-1;

	for(i=2;i<=n/2+1;i++)
		for(j=2;j*i<=n;j++)
			v[i*j]=-1;

	long long inceput=1;

	for(i=n;i>0;i--)
		if(v[i]==0)
		{
			k++;
			if(k<=1000)
				inceput=i;
		}

	printf("%lld\n",k);

	for(i=inceput;i<=n;i++)
		if(v[i]==0)
			printf("%lld ",i);

	return 0;
}