#include <bits/stdc++.h>
using namespace std;
const int MAX = 100007;
int n;
int f[MAX];
int g[MAX];
int h[MAX];
int s[MAX];
int m;
bool test() {
  for (int i = 0; i < m; i++)
    if (i + 1 != g[h[i] - 1]) return false;
  return true;
}
int main() {
  cin >> n;
  for (int i = 0; i < n; i++) {
    scanf("%d", &f[i]);
    s[i] = f[i];
    if (s[i] > n || s[i] <= 0) {
      puts("-1");
      return 0;
    }
  }
  sort(s, s + n);
  m = unique(s, s + n) - s;
  for (int i = 0; i < n; i++) {
    g[i] = lower_bound(s, s + m, f[i]) - s + 1;
  }
  for (int i = 0; i < m; i++) {
    h[i] = s[i];
  }
  if (test()) {
    cout << m << endl;
    for (int i = 0; i < n; i++) cout << g[i] << ' ';
    cout << endl;
    for (int i = 0; i < m; i++) cout << h[i] << ' ';
    cout << endl;
  } else
    cout << -1 << endl;
  return 0;
}
