func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, m, i, j;   int main() {     ios::sync_with_stdio(false);     cin >> n;     cout << 3 * n / 2 <<   n ;     for (i = 2; i <= n; i += 2) cout << i <<    ;     for (i = 1; i <= n; i += 2) cout << i <<    ;     for (i = 2; i <= n; i += 2) cout << i <<    ;     return 0;   }   