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Contest: Task: Related: TaskE TaskG

Score : $500$ points

Problem Statement

We have a permutation $P=(P_1,P_2,\ldots,P_N)$ of $(1,2,\ldots,N)$.

There are $M$ kinds of operations available to you. Operation $i$ swaps the $a_i$-th and $b_i$-th elements of $P$.

Is it possible to sort $P$ in ascending order by doing at most $5\times 10^5$ operations in total in any order?

If it is possible, give one such sequence of operations. Otherwise, report so.

Constraints

  • $2\leq N \leq 1000$
  • $P$ is a permutation of $(1,2,\ldots,N)$.
  • $1\leq M \leq \min(2\times 10^5, \frac{N(N-1)}{2})$
  • $1\leq a_i \lt b_i\leq N$
  • $(a_i,b_i)\neq (a_j,b_j)$ if $i\neq j$.
  • All values in input are integers.

Input

Input is given from Standard Input in the following format:

$N$
$P_1$ $P_2$ $\ldots$ $P_N$
$M$
$a_1$ $b_1$
$a_2$ $b_2$
$\vdots$
$a_M$ $b_M$

Output

If it is possible to sort $P$ in ascending order, print the following:

$K$
$c_1$ $c_2$ $\ldots$ $c_K$

Here, $K$ represents the number of operations to do, and $c_i$ $(1\leq i \leq K)$ means the $i$-th operation to do is Operation $c_i$.
Note that $0\leq K \leq 5\times 10^5$ must hold.

If it is impossible to sort $P$ in ascending order, print -1.

Sample Input 1

6
5 3 2 4 6 1
4
1 5
5 6
1 2
2 3

Sample Output 1

3
4 2 1

$P$ changes as follows: $(5,3,2,4,6,1)\to (5,2,3,4,6,1)\to (5,2,3,4,1,6)\to (1,2,3,4,5,6)$.

Sample Input 2

5
3 4 1 2 5
2
1 3
2 5

Sample Output 2

-1

We cannot sort $P$ in ascending order.

Sample Input 3

4
1 2 3 4
6
1 2
1 3
1 4
2 3
2 4
3 4

Sample Output 3

0

$P$ may already be sorted in ascending order.

Additionally, here is another accepted output:

4
5 5 5 5

Note that it is not required to minimize the number of operations.