func_code_string: #include <bits/stdc++.h>   using namespace std;   const int maxn = 100010;   int i, j, k, n, m, vis[maxn], cnt, Q[maxn], top;   void dfs(int now) {     vis[now]++;     if (!vis[now * 2 % n]) dfs(now * 2 % n);     if (!vis[(now * 2 + 1) % n]) dfs((now * 2 + 1) % n);     Q[++top] = now;   }   int main() {     cin >> n;     if (n & 1)       cout << -1 << endl;     else {       dfs(0);       while (top) cout << Q[top--] <<    ;       cout << 0 << endl;     }     return 0;   }   