#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 10;
int n, p[maxn], f[maxn], g[maxn], h[maxn];
int find(int x) { return p[x] == x ? x : p[x] = find(p[x]); }
vector<int> G[maxn];
int main(void) {
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) p[i] = i;
  for (int i = 1; i <= n; i++) {
    scanf("%d", &f[i]);
  }
  for (int i = 1; i <= n; i++) {
    int u = f[i], v = i;
    int fu = find(u);
    int fv = find(v);
    if (fu == fv) continue;
    if (fu < fv) {
      G[fu].push_back(v);
      p[fv] = fu;
    } else {
      G[fv].push_back(u);
      p[fu] = fv;
    }
  }
  int m = 0;
  for (int i = 1; i <= n; i++) {
    if (p[i] == i) {
      g[i] = ++m;
      for (int k = 0; k < G[i].size(); k++) {
        g[G[i][k]] = m;
      }
    }
  }
  int flag = 1;
  for (int i = 1; i <= n; i++) {
    if (h[g[i]] == 0)
      h[g[i]] = f[i];
    else {
      if (f[i] != h[g[i]]) {
        flag = 0;
        break;
      }
    }
  }
  if (flag == 0)
    printf("-1\n");
  else {
    printf("%d\n", m);
    for (int i = 1; i <= n; i++) {
      if (i == 1)
        printf("%d", g[i]);
      else
        printf(" %d", g[i]);
    }
    printf("\n");
    for (int i = 1; i <= m; i++) {
      if (i == 1)
        printf("%d", h[i]);
      else
        printf(" %d", h[i]);
    }
  }
  return 0;
}
