#include <stdio.h>
#include <string.h>

#define NMAX 2000010

long n;
char ciur[NMAX];
long prime[1010];
int h;
long nr;


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

	scanf("%ld", &n);

	for(i = 2; i <= n; ++i)
		if(ciur[i] == 0)
			for(++nr, j = 2; i*j <= n; ++j)
				ciur[i*j] = 1;

	for(i = n; i >= 2; --i)
	{
		if(!ciur[i])
			prime[++h] = i;
		if(h == 1000) break;
	}
	printf("%ld\n", nr);

	while(h)
		printf("%ld ", prime[h--]);

	return 0;
}