A9188. Sereja ans Anagrams

Sereja has two sequences $a$ and $b$ and number $p$ . Sequence $a$ consists of $n$ integers $a_{1},a_{2},...,a_{n}$ . Similarly, sequence $b$ consists of $m$ integers $b_{1},b_{2},...,b_{m}$ . As usual, Sereja studies the sequences he has. Today he wants to find the number of positions $q$ $(q+(m-1)·p<=n; q>=1)$ , such that sequence $b$ can be obtained from sequence $a_{q},a_{q+p},a_{q+2p},...,a_{q+(m-1)p}$ by rearranging elements.

Sereja needs to rush to the gym, so he asked to find all the described positions of $q$ .

The first line contains three integers $n$ , $m$ and $p$ $(1<=n,m<=2·10^{5},1<=p<=2·10^{5})$ . The next line contains $n$ integers $a_{1}$ , $a_{2}$ , $...$ , $a_{n}$ $(1<=a_{i}<=10^{9})$ . The next line contains $m$ integers $b_{1}$ , $b_{2}$ , $...$ , $b_{m}$ $(1<=b_{i}<=10^{9})$ .

In the first line print the number of valid $q$ s. In the second line, print the valid values in the increasing order.