func_code_string: #include <bits/stdc++.h>   using namespace std;   int prime(int n) {     int val = sqrt(n), counter = 0;     ;     if (n == 1) return false;     for (int i = 2; i <= val; i++) {       if (!(n % i)) counter++;     }     if (counter) return -1;     return n;   }   int root(int n) {     int val = sqrt(n);     int x = n, flag = 0;     ;     for (int i = 2; i <= val; i++) {       if (!(n % i)) {         while (n > 1) {           if (n % i != 0) {             flag = 1;             break;           }           n = n / i;         }         if (flag) return -1;         return x;       }     }     return -1;   }   int main() {     int n, counter = 0, val, val1;     vector<int> vec;     ;     cin >> n;     for (int i = 2; i <= n; i++) {       val = prime(i);       val1 = root(i);       if (val != -1) {         counter++;         vec.push_back(val);       } else if (val1 != -1) {         counter++;         vec.push_back(val1);       }     }     cout << counter << endl;     for (int i = 0; i < counter; i++) cout << vec[i] <<    ;     cout << endl;     return 0;   }   