#include <bits/stdc++.h>   using namespace std;   bool isPrime(int n) {     if (n <= 1) return false;     for (int i = 2; i < n; i++)       if (n % i == 0) return false;     return true;   }   int main() {     ios_base::sync_with_stdio(false), cin.tie(NULL), cout.tie(NULL);     int n;     cin >> n;     vector<int> v;     if (n == 1) {       cout <<  0 ;       return 0;     }     int temp;     for (long long int i = (2); i <= (n); i++) {       temp = i;       if (isPrime(i)) {         while (temp <= n) {           v.push_back(temp);           temp *= i;         }       }     }     cout << v.size() << endl;     for (auto i = v.begin(); i != v.end(); i++) cout << *i <<    ;   }   