#include <bits/stdc++.h>
using namespace std;
const int mod = 1e9 + 7;
int a[100023];
bool vis[100023];
vector<int> ind[100023];
int g[100023];
int h[1000023];
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n;
  cin >> n;
  int cnt = 0;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
    if (!vis[a[i]]) cnt++;
    vis[a[i]] = true;
    ind[a[i]].push_back(i);
  }
  for (int i = 1; i <= n; i++) {
    if (vis[i] and a[i] != i) {
      cout << -1 << endl;
      return 0;
    }
  }
  cout << cnt << "\n";
  int val = 1;
  for (int i = 1; i <= n; i++) {
    if (!vis[i]) continue;
    for (int j = 0; j < ind[i].size(); j++) {
      g[ind[i][j]] = val;
    }
    h[val] = i;
    val++;
  }
  for (int i = 1; i <= n; i++) cout << g[i] << " ";
  cout << endl;
  for (int i = 1; i <= cnt; i++) cout << h[i] << " ";
  cout << endl;
  return 0;
}
