func_code_string: #include <bits/stdc++.h>   const int maxN = 3e5 + 5;   int main() {     if (fopen( iput.txt ,  r )) {       freopen( iput.txt ,  r , stdin);       freopen( oput.txt ,  w , stdout);     }     int n;     scanf( %d , &n);     printf( %d n , n / 2 * 2 + n - n / 2);     printf( 2  );     for (int i = 4; i <= n; i += 2) printf( %d  , i);     for (int i = 1; i <= n; i += 2) printf( %d  , i);     for (int i = 2; i <= n; i += 2) printf( %d  , i);     return 0;   }   