#include <bits/stdc++.h>

 const int INF = 0x3f3f3f3f;

 inline void read(long long &x)

 {

     x = ;char ch = getchar();char c = ch;

     while(ch < '' || ch > '')c = ch, ch = getchar();

     while(ch <= '' && ch >= '')x = x *  + ch - '',ch = getchar();

     if(c == '-')x = -x;

 }

 long long x;

 long long a;

 bool IsPrime(long long k)

 {

     long long a = sqrt(k);

     for(int i = ;i <= a;i ++)

     {

         if(k % i == )

         {

             return false;

         }

     }

     return true;

 }

 long long prime[];

 long long num[];

 int head,tail;

 int main()

 {

     read(x);

     if(x < ){printf("");return ;}

     if(x < ){printf("1\n2");return ;}

     if(x < ){printf("2\n2\n3");return ;}

     if(x < ){printf("3\n2\n3\n5");return ;}

     if(x < ){printf("4\n2\n3\n5\n7");return ;}

     head = ;

     tail = ;

     prime[] = ;

     prime[] = ;

     prime[] = ;

     prime[] = ;

     num[] = ;

     num[] = ;

     num[] = ;

     num[] = ;

     while(head <= tail)

     {

         for(int i = ;i <= ;i ++)

         {

             long long tmp = prime[head] *  + num[i];

             if(tmp <= x && IsPrime(tmp))

             {

                 prime[++tail] = tmp;

             }

             if(tmp > x)goto L1;

         }

         head ++;

     }

 L1:

     printf("%d\n", tail);

     for(int i = ;i <= tail;i ++)

     {

         printf("%d\n", prime[i]);

     }

     return ;

 }