#include <bits/stdc++.h>
using namespace std;
int f[100005], fi[100005];
vector<int> F[100005];
int M[1000005];
int g[1000005];
int main() {
  int n;
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> f[i];
    F[f[i]].push_back(i);
    fi[f[i]] = i;
  }
  int m = 1;
  for (int i = 1; i <= n; i++) {
    if (F[i].size()) {
      M[m] = i;
      m++;
    }
  }
  for (int i = 1; i < m; i++) {
    int x = M[i];
    int y = x;
    for (int j = 0; j < F[y].size(); j++) {
      g[F[y][j]] = i;
    }
  }
  int flag = 1;
  for (int i = 1; i < m; i++) {
    if (g[M[i]] != i) {
      flag = 0;
      break;
    }
  }
  for (int i = 1; i <= n; i++) {
    if (M[g[i]] != f[i]) {
      flag = 0;
      break;
    }
  }
  if (!flag) {
    cout << -1;
    return 0;
  }
  m--;
  cout << m << "\n";
  for (int i = 1; i <= n; i++) {
    cout << g[i] << " ";
  }
  cout << "\n";
  for (int i = 1; i <= m; i++) {
    cout << M[i] << " ";
  }
  return 0;
}
