#include <bits/stdc++.h>
using namespace std;
const int MAX_N = 1e5 + 10;
int f[MAX_N], g[MAX_N], h[MAX_N], pos[MAX_N];
vector<int> adj[MAX_N];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int n;
  cin >> n;
  int m = 0;
  for (int i = 1; i <= n; i++) {
    cin >> f[i];
    if (adj[f[i]].empty()) {
      m++;
      h[m] = f[i];
      pos[f[i]] = m;
    }
    adj[f[i]].push_back(i);
  }
  for (int i = 1; i <= n; i++) {
    for (int j = 0; j < adj[i].size(); j++) {
      if (g[adj[i][j]] != 0) {
        cout << "-1\n";
        return 0;
      }
      g[adj[i][j]] = pos[i];
    }
  }
  for (int i = 1; i <= n; i++) {
    if (!g[i]) {
      cout << "-1\n";
      return 0;
    }
  }
  for (int i = 1; i <= m; i++) {
    if (g[h[i]] != i) {
      cout << "-1\n";
      return 0;
    }
  }
  cout << m << "\n";
  for (int i = 1; i <= n; i++) {
    cout << g[i];
    if (i < n) cout << " ";
  }
  cout << "\n";
  for (int i = 1; i <= m; i++) {
    cout << h[i];
    if (i < m) cout << " ";
  }
  cout << "\n";
}
