#include <bits/stdc++.h>
using namespace std;
int n, a[100001], g[100001], h[100001], m;
set<int> events[100001];
int main() {
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) events[i].clear();
  for (int i = 1; i <= n; i++) scanf("%d", &a[i]), events[a[i]].insert(i);
  m = 0;
  bool ok = true;
  for (int i = 1; i <= n; ++i)
    if (!events[i].empty())
      if (events[i].find(i) == events[i].end()) {
        ok = false;
        break;
      }
  if (!ok) {
    printf("-1\n");
    return 0;
  }
  for (int i = 1; i <= n; i++)
    if (!events[i].empty()) {
      h[++m] = i;
      for (set<int>::iterator itr = events[i].begin(); itr != events[i].end();
           ++itr)
        g[*itr] = m;
    }
  printf("%d\n", m);
  for (int i = 1; i <= n; i++) printf("%d ", g[i]);
  printf("\n");
  for (int i = 1; i <= m; i++) printf("%d ", h[i]);
  printf("\n");
}
