Given two arrays of integers, find their longest common subsequence.
A subsequence is a sequence of array elements from left to right that can contain gaps. A common subsequence is a subsequence that appears in both arrays.
The first line has two integers $n$ and $m$ : the sizes of the arrays.
The second line has $n$ integers $a_1,a_2,\dots,a_n$ : the contents of the first array.
The third line has $m$ integers $b_1,b_2,\dots,b_m$ : the contents of the second array.
First print the length of the longest common subsequence.
After that, print an example of such a sequence. If there are several solutions, you can print any of them.
8 6 3 1 3 2 7 4 8 2 6 5 1 2 3 4· \n · · · · · · · \n · · · · · \n
3 1 2 4\n · · \n