Artsem and Saunders

2000ms

524288K

Description:

Artsem has a friend Saunders from University of Chicago. Saunders presented him with the following problem.

Let [n] denote the set {1, ..., n}. We will also write f: [x] → [y] when a function f is defined in integer points 1, ..., x, and all its values are integers from 1 to y.

Now then, you are given a function f: [n] → [n]. Your task is to find a positive integer m, and two functions g: [n] → [m], h: [m] → [n], such that g(h(x)) = x for all $\text{[math]}$ , and h(g(x)) = f(x) for all $\text{[math]}$ , or determine that finding these is impossible.

Input:

The first line contains an integer n (1 ≤ n ≤ 10⁵).

The second line contains n space-separated integers — values f(1), ..., f(n) (1 ≤ f(i) ≤ n).

Output:

If there is no answer, print one integer -1.

Otherwise, on the first line print the number m (1 ≤ m ≤ 10⁶). On the second line print n numbers g(1), ..., g(n). On the third line print m numbers h(1), ..., h(m).

If there are several correct answers, you may output any of them. It is guaranteed that if a valid answer exists, then there is an answer satisfying the above restrictions.

Sample Input:

3
1 2 3

Sample Output:

3
1 2 3
1 2 3

Sample Input:

3
2 2 2

Sample Output:

1
1 1 1
2

Sample Input:

2
2 1

Sample Output:

-1

Informação

Provedor Codeforces

Código CF765D