#include <bits/stdc++.h>
using namespace std;
long long dp[int(3e5 + 11)];
long long fx[int(3e5 + 11)];
long long fe[int(3e5 + 11)];
long long pas[int(3e5 + 11)];
long long pp[int(3e5 + 11)];
long long f[int(3e5 + 11)];
vector<long long> v[int(3e5 + 11)];
vector<long long> cl[int(3e5 + 11)];
long long a[int(3e5 + 11)];
int main() {
  long long n, b, m = 0;
  cin >> n;
  long long k = 0;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
    if (i == a[i]) {
      pp[i] = k;
      pas[k] = i;
      fe[a[i]] = 1;
      k++;
    }
    if (!fx[a[i]]) m++;
    fx[a[i]] = 1;
  }
  for (int i = 0; i <= n; i++) {
    if (fx[i] && !fe[i]) {
      cout << -1;
      return 0;
    }
  }
  cout << m << endl;
  for (int i = 1; i <= n; i++) {
    cout << pp[a[i]] + 1 << " ";
  }
  cout << endl;
  for (int i = 0; i < m; i++) {
    cout << pas[i] << " ";
  }
  return 0;
}
