func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n;     cin >> n;     if (n == 2)       cout << 1 << endl << 1;     else if (n == 3)       cout << 2 << endl <<  1 3 ;     else {       cout << n << endl;       for (int i = 2; i <= n; i += 2) cout << i <<    ;       for (int i = 1; i <= n; i += 2) cout << i <<    ;     }     return 0;   }   