Cipher

Time Limit: 2 Seconds
Memory Limit: 65536 KB

The village of Martyshkino was fortunate to hold the 1/256-final of the world
championship in computer programming. The General Organizer of the championship
(who was also The Jury Chairman) decided that no precautions are excessive and
ciphered all secret tests by repeatedly intermixing them. In order to make the
cipher stronger he did the mixing as many times, as many numbers were in the
test. We should note, that all the numbers were natural and complied with the
condition: 1 <= Xi <= N, where N is the amount of numbers in the test.

The mixing procedure consisted of the following. The initial or the resulting
after the previous mixing sequence was split into two groups. The size of the
first group was defined by the value of the first number of the current sequence,
the second (maybe empty) group included all the remaining numbers. After that
there were three steps: writing the numbers of the first group in the back order,
writing the numbers of the second group in the back order, writing the numbers
of the whole sequence in the back order.

It's obvious that after executing N procedures of such a brilliant mixing no
spy would be able to restore the secret test (except for the General Organizer,
of course). Your task is slightly easier: you need to find the first member
of the sequence after it has been ciphered.

1 <= n <= 61099

**Input**

The first line of the input file contains the number N and all the following
lines (there may be several of them) contain N elements of a numeral sequence,
separated by one or several spaces.

Process to the end of file.

**Output**

The output file must contain the solution: the first element of the sequence
after mixing it.

**Sample Input**

4

2 4 1 1

**Sample Output**

1

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