func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n;     cin >> n;     int sum = n;     sum += n / 2;     cout << sum << endl;     for (int i = 2; i <= n; i += 2) {       cout << i <<    ;     }     for (int i = 1; i <= n; i += 2) {       cout << i <<    ;     }     for (int i = 2; i <= n; i += 2) {       cout << i <<    ;     }     return 0;   }   