#include <stdio.h>
#include <fstream>
using namespace std;

#define in "ciur.in"
#define out "ciur.out"
#define dim 2000001

int N;
int Nr[1001];
bool Sel[dim];

int main()
{
    memset(Sel,0,sizeof(Sel));
    freopen(in,"r",stdin);
    freopen(out,"w",stdout);
    
    scanf("%d", &N);
    
    for ( int i = 2; i*i <= N; i++ )
    {
        if ( Sel[i] ) continue;
        for ( int j = 2; i*j <= N; j++ ) Sel[i*j] = 1;
    }
    
    int size = 0;
    
    for ( int i = N; i >= 2; i-- )
    {
        if ( !Sel[i] ) Nr[++size] = i;
        
        if ( size == 1000 ) break;
    }
    
    printf("%d\n",size);
    for ( ; size; size-- )
        printf("%d ", Nr[size]);
}