void solve() { int n ; cin >> n;

string s ; cin >> s;

vector<int> check(n);

for (int i = 0 ; i < n ; i++) check[i] = (s[i] == '1');

vector<int>a(n); input(a);

vector<int>indegree(n);

for (int i = 0 ; i < n ; i++)

{

    indegree[--a[i]]++;

}

queue<int> q;

vector<int> ans;

for (int i = 0 ; i < n ; i++)

{

    if (indegree[i] == 0)q.push(i);

}

while (!q.empty())

{

    int u = q.front(); q.pop();

    if (check[u])

    {

       ans.push_back(u);

       check[u] = !check[u];

       check[a[u]] = !check[a[u]];

    }

    indegree[a[u]]--;

    if (indegree[a[u]] == 0)q.push(a[u]);

}

for (int i = 0 ; i < n ; i++)

{
    if (indegree[i])

    {

       int j = i;

       int length = 0 , track = 0 , res = 0;


       while (indegree[j])

       {

         if (check[j]) track ^= 1;

         res += track;

         indegree[j] = 0;

         length++;

         j = a[j];

       }

       if (track == 1)

       {

         cout << -1 << endl;

         return;

       }

       for (int k = 0  ; k < length ; k++)

       {

         if (check[j]) track ^= 1;

         if (track == (res < length- res))

         {
          ans.push_back(j);
         }
         j = a[j];
       }
    }
}
cout << ans.size() << endl;
for (auto a : ans) cout << a + 1 << " ";
cout << endl;

}