#include <bits/stdc++.h>
using namespace std;
double PI = 4.00 * (atan(1));
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long int n;
  cin >> n;
  long long int fun[n + 1];
  set<long long int> s1;
  for (long long int i = 1; i <= n; i++) {
    cin >> fun[i];
  }
  bool check = true;
  for (long long int i = 1; i <= n; i++) {
    if (fun[fun[i]] != fun[i]) {
      check = false;
    } else {
      s1.insert(fun[i]);
    }
  }
  if (check == false) {
    cout << "-1";
    exit(0);
  }
  vector<long long int> final(s1.begin(), s1.end());
  long long int size = final.size();
  map<long long int, long long int> pos;
  for (long long int i = 0; i < size; i++) {
    pos[final[i]] = i + 1;
  }
  cout << size << endl;
  for (long long int i = 1; i <= n; i++) {
    cout << pos[fun[i]] << " ";
  }
  cout << endl;
  for (long long int i = 0; i < size; i++) {
    cout << final[i] << " ";
  }
  return 0;
}
