#include <bits/stdc++.h>
using namespace std;
const int MAXN = 1e5 + 10;
int n;
int f[MAXN];
bool read() {
  if (scanf("%d", &n) < 1) {
    return 0;
  }
  for (int i = 0; i < int(n); ++i) {
    scanf("%d", &f[i]);
    --f[i];
  }
  return 1;
}
vector<int> inv_f[MAXN];
int g[MAXN];
int h[MAXN];
bool solve() {
  for (int i = 0; i < int(n); ++i) {
    inv_f[i].clear();
  }
  for (int i = 0; i < int(n); ++i) {
    inv_f[f[i]].push_back(i);
  }
  memset(g, -1, sizeof g);
  int m = 0;
  for (int i = 0; i < int(n); ++i) {
    if (inv_f[i].empty()) {
      continue;
    }
    if (f[i] != i) {
      return 0;
    }
    for (int j : inv_f[i]) {
      g[j] = m;
    }
    h[m] = i;
    ++m;
  }
  for (int x = 0; x < int(m); ++x) {
    assert(g[h[x]] == x);
  }
  for (int x = 0; x < int(n); ++x) {
    assert(h[g[x]] == f[x]);
  }
  printf("%d\n", m);
  for (int i = 0; i < int(n); ++i) {
    printf("%d ", g[i] + 1);
  }
  puts("");
  for (int i = 0; i < int(m); ++i) {
    printf("%d ", h[i] + 1);
  }
  puts("");
  return 1;
}
int main() {
  while (read()) {
    if (!solve()) {
      puts("-1");
    }
  }
  return 0;
}
