#include <bits/stdc++.h>
using namespace std;
const int inf = 1e9 + 7;
const long long llinf = 1ll * inf * inf;
const double eps = 1e-12;
const int N = 1e5 + 10;
int f[N], h[N], g[N];
int main() {
  int n;
  scanf("%d", &n);
  for (int i = 1; i <= int(n); ++i) scanf("%d", &f[i]);
  map<int, vector<int> > uf;
  for (int i = 1; i <= int(n); ++i) uf[f[i]].push_back(i);
  int m = uf.size();
  auto itr = uf.begin();
  for (int x = 1; x <= m; ++x) {
    h[x] = itr->first;
    vector<int> nv = itr->second;
    itr++;
    for (int y : nv) g[y] = x;
  }
  int bad = 0;
  for (int x = 1; x <= m; ++x)
    if (g[h[x]] != x) bad = 1;
  for (int x = 1; x <= n; ++x)
    if (h[g[x]] != f[x]) bad = 1;
  if (bad)
    puts("-1");
  else {
    printf("%d\n", m);
    for (int x = 1; x <= int(n); ++x) printf("%d%c", g[x], x == n ? '\n' : ' ');
    for (int x = 1; x <= int(m); ++x) printf("%d%c", h[x], x == m ? '\n' : ' ');
  }
  return 0;
}
