Ancient Berland Hieroglyphs

1000ms

262144K

Description:

Polycarpus enjoys studying Berland hieroglyphs. Once Polycarp got hold of two ancient Berland pictures, on each of which was drawn a circle of hieroglyphs. We know that no hieroglyph occurs twice in either the first or the second circle (but in can occur once in each of them).

Polycarpus wants to save these pictures on his laptop, but the problem is, laptops do not allow to write hieroglyphs circles. So Polycarp had to break each circle and write down all of its hieroglyphs in a clockwise order in one line. A line obtained from the first circle will be called a, and the line obtained from the second one will be called b.

There are quite many ways to break hieroglyphic circles, so Polycarpus chooses the method, that makes the length of the largest substring of string a, which occurs as a subsequence in string b, maximum.

Help Polycarpus — find the maximum possible length of the desired substring (subsequence) if the first and the second circles are broken optimally.

The length of string s is the number of characters in it. If we denote the length of string s as |s|, we can write the string as s = s₁s₂... s_|s|.

A substring of s is a non-empty string x = s[a... b] = s_as_a + 1... s_b (1 ≤ a ≤ b ≤ |s|). For example, "code" and "force" are substrings of "codeforces", while "coders" is not.

A subsequence of s is a non-empty string y = s[p₁p₂... p_|y|] = s_p₁s_p₂... s_{p_|y|} (1 ≤ p₁ < p₂ < ... < p_|y| ≤ |s|). For example, "coders" is a subsequence of "codeforces".

Input:

The first line contains two integers l_a and l_b (1 ≤ l_a, l_b ≤ 1000000) — the number of hieroglyphs in the first and second circles, respectively.

Below, due to difficulties with encoding of Berland hieroglyphs, they are given as integers from 1 to 10⁶.

The second line contains l_a integers — the hieroglyphs in the first picture, in the clockwise order, starting with one of them.

The third line contains l_b integers — the hieroglyphs in the second picture, in the clockwise order, starting with one of them.

It is guaranteed that the first circle doesn't contain a hieroglyph, which occurs twice. The second circle also has this property.

Output:

Print a single number — the maximum length of the common substring and subsequence. If at any way of breaking the circles it does not exist, print 0.

Sample Input:

5 4
1 2 3 4 5
1 3 5 6

Sample Output:

Sample Input:

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

Sample Output:

Sample Input:

3 3
1 2 3
3 2 1

Sample Output:

Note:

In the first test Polycarpus picks a string that consists of hieroglyphs 5 and 1, and in the second sample — from hieroglyphs 1, 3 and 5.

Informação

Provedor Codeforces

Código CF164B