#include<stdio.h>

char v[2000005];
int main()
{long n,i,j,m=0,w[1024];

freopen("ciur.in","r",stdin);
freopen("ciur.out","w",stdout);
scanf(" %ld",&n);

for(i=2;i<=n;++i)if(!v[i]){++m;for(j=i+i;j<=n;j+=i)v[j]=1;}
j=0;
printf("%ld\n",m);
for(i=n;i>=2&&j<1000;--i)if(!v[i]){w[++j]=i;}
for(;j>=1;--j)printf("%ld ",w[j]);

printf("\n"); 

return 0;
}