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문제

A number from 1 to n is inscribed in each cell of a 2 × n grid in such a way that each number appears exactly twice in the grid and each column contains two different numbers. An example of such a configuration is depicted below.

We would like to colour each of the cells white or gray in such a way that cells located in the same column receive different colours and cells containing same number receive different colours. An example of such a colouring of the grid from the previous figure is depicted below.

How many such colourings exist?

입력

The first line of the standard input contains one integer n (2 ≤ n ≤ 100). Each of the following two lines contains n integers in the range [1, n], separated by single spaces. The numbers in these lines represent numbers inscribed in consecutive cells of the grid.

출력

 

The first and only line of the standard output should contain a single integer - the number of different colourings of the grid with two colours that fulfill the described conditions.

예제 입력 1

5
1 5 3 1 5
4 2 2 4 3

예제 출력 1

4

힌트

Please note that the example describes the grid from the above figures.