#include<cstdio>

const long MAX=2000100;

long b[1010],i,j,n,nr;
bool ok;
unsigned char v[(MAX >> 3)+2];

int main(){
	freopen("ciur.in","r",stdin);
	freopen("ciur.out","w",stdout);
	scanf("%ld",&n);
	for(i=1;((i*i) << 1)+(i << 1)<=n;i++)
		if((v[i >> 3] & (1 << (i & 7)))==0)
			for(j=((i*i) << 1)+(i << 1);(j << 1)+1<=n;j+=(i << 1)+1)
				v[j >> 3]|=(1 << (j & 7));
	b[1]=2;b[0]=1;nr=1;
	for(i=1;i<=n;i++)
		if((v[i >> 3] & (1 << (i & 7)))==0)
			if((i << 1)+1<=n){
				b[++b[0]]=2*i+1;
				nr++;
				if(b[0]>1000){
					ok=1;
					b[1]=b[b[0]];
					b[0]=1;
				}
			}
	printf("%ld\n",nr);
	if(ok==0)
		for(i=1;i<=b[0];i++)
			printf("%ld ",b[i]);
	else{
		for(i=b[0]+1;i<=1000;i++)
			printf("%ld ",b[i]);
		for(i=1;i<=b[0];i++)
			printf("%ld ",b[i]);
	}
	printf("\n");
	fclose(stdin);
	fclose(stdout);
	return 0;
}