#include <bits/stdc++.h>
using namespace std;
int n, f[100009];
bool m1[100009], m2[100009];
int m, id[100009], rid[100009];
bool proc() {
  for (int i = 0; i < n; i++)
    if (m1[i] && !m2[i]) return 0;
  return 1;
}
int main() {
  while (scanf("%d", &n) == 1) {
    m = 0;
    memset(m1, 0, sizeof(m1));
    memset(m2, 0, sizeof(m2));
    memset(id, -1, sizeof(id));
    for (int i = 0; i < n; i++) {
      scanf("%d", &f[i]);
      f[i]--;
      if (!m1[f[i]]) {
        m1[f[i]] = 1;
        rid[m] = f[i];
        id[f[i]] = m++;
      }
      if (i == f[i]) m2[f[i]] = 1;
    }
    if (!proc())
      puts("-1");
    else {
      printf("%d\n", m);
      bool fp = 1;
      for (int i = 0; i < n; i++) {
        if (fp)
          fp = 0;
        else
          printf(" ");
        printf("%d", id[f[i]] + 1);
      }
      puts("");
      fp = 1;
      for (int i = 0; i < m; i++) {
        if (fp)
          fp = 0;
        else
          printf(" ");
        printf("%d", rid[i] + 1);
      }
      puts("");
    }
  }
  return 0;
}
