#include <bits/stdc++.h>
using namespace std;
template <typename T>
inline bool chkmin(T &a, const T &b) {
  return a > b ? a = b, 1 : 0;
}
template <typename T>
inline bool chkmax(T &a, const T &b) {
  return a < b ? a = b, 1 : 0;
}
const int oo = 0x3f3f3f3f;
const int maxn = 100100;
int n, m;
int a[maxn + 5];
int b[maxn + 5];
int c[maxn + 5];
int id[maxn + 5];
int main() {
  scanf("%d", &n);
  memset(id, -1, sizeof id);
  memset(c, -1, sizeof c);
  m = 0;
  for (int i = (0), i_end_ = (n); i < i_end_; ++i) {
    scanf("%d", a + i), --a[i];
    if (!~id[a[i]]) id[a[i]] = m++;
    b[i] = id[a[i]];
    if (a[i] == i) c[id[a[i]]] = i;
  }
  for (int i = (0), i_end_ = (m); i < i_end_; ++i)
    if (!~c[i]) {
      printf("-1\n");
      return 0;
    }
  for (int i = (0), i_end_ = (m); i < i_end_; ++i) assert(b[c[i]] == i);
  for (int i = (0), i_end_ = (n); i < i_end_; ++i) assert(c[b[i]] == a[i]);
  printf("%d\n", m);
  for (int i = (0), i_end_ = (n); i < i_end_; ++i) printf("%d ", b[i] + 1);
  printf("\n");
  for (int i = (0), i_end_ = (m); i < i_end_; ++i) printf("%d ", c[i] + 1);
  printf("\n");
  return 0;
}
