#include <bits/stdc++.h>
using namespace std;
const long long N = 1e5 + 5;
long long f[N], n, m = 0, g[N], h[N];
set<long long> s;
int main() {
  ios_base::sync_with_stdio(false);
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> f[i];
    if (f[i] == i) {
      s.insert(i);
      m++;
      h[m] = i;
      g[i] = m;
    }
  }
  long long flag = 1;
  for (int i = 1; i <= n; i++)
    if (s.find(f[i]) == s.end()) flag = 0;
  if (!flag) {
    cout << -1;
    return 0;
  }
  for (int i = 1; i <= n; i++)
    if (i != f[i]) g[i] = g[f[i]];
  cout << m << endl;
  for (int i = 1; i <= n; i++) cout << g[i] << " ";
  cout << endl;
  for (int i = 1; i <= m; i++) cout << h[i] << " ";
  cout << endl;
}
