#include <bits/stdc++.h>
using namespace std;
inline int toInt(string s) {
  int v;
  istringstream sin(s);
  sin >> v;
  return v;
}
template <class T>
inline string toString(T x) {
  ostringstream sout;
  sout << x;
  return sout.str();
}
int a[111111];
int c[111111];
int g[111111];
int h[111111];
int main() {
  int n, k = 0;
  scanf("%d", &n);
  for (int i = (0); i < (n); ++i) {
    scanf("%d", &a[i]);
    a[i]--;
  }
  for (int i = (0); i < (n); ++i)
    if (a[a[i]] != a[i]) k = -1;
  if (k == -1) {
    printf("-1\n");
    return 0;
  }
  memset(g, -1, sizeof(g));
  for (int i = (0); i < (n); ++i) {
    if (g[a[i]] == -1) {
      g[i] = g[a[i]] = k;
      h[k] = a[i];
      k++;
    }
    g[i] = g[a[i]];
  }
  printf("%d\n", k);
  for (int i = (0); i < (n); ++i) printf("%d ", g[i] + 1);
  printf("\n");
  for (int i = (0); i < (k); ++i) printf("%d ", h[i] + 1);
  printf("\n");
  return 0;
}
