#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 10;
const int M = 1e6 + 10;
int n, m;
int f[M];
int g[M], h[M];
vector<int> val[M];
int main() {
  int flag = 1;
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) {
    scanf("%d", f + i);
    if (f[i] == i) {
      m++;
      h[m] = i;
    }
  }
  for (int i = 1; i <= n; i++) {
    if (f[f[i]] != f[i]) {
      flag = 0;
    }
  }
  for (int i = 1; i <= n; i++) {
    int key = lower_bound(h + 1, h + 1 + m, f[i]) - h;
    val[key].push_back(i);
  }
  if (flag == 0) {
    printf("-1\n");
    return 0;
  }
  printf("%d\n", m);
  for (int i = 1; i <= n; i++) {
    for (int j = 0; j < val[i].size(); j++) {
      g[val[i][j]] = i;
    }
  }
  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");
  return 0;
}
