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50819 - Linked Numbers

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Time limit 2000/4000/4000/4000 ms. Memory limit 65000/65000/65000/65000 Kb.
Question by Ibrahim Mesecan.

Linked Numbers

Assume that you are given the n numbers. Find the maximum length of number ordering such that the last digit of one number (a_n) is the same as the first digit of the next number (a_n+1). For example the following series complies the Linked Numbers property:

  12 235 514

However the following series does not:

   12 235 415

because second number 235 ends with 5, but the third number 415 starts with 4.

Question: You will be given n positive integer. By possible replacements, find the length of longest linked numbers.

Input specification
In the first line, you will be given a number: The number of numbers(n) 1 ≤ n ≤ 30. Then, in the following n lines, you will be given n integers which are between 0 and 12,000.

Output specification
Show the length of the longest linked list

Sample Input
4 235 12 317 514 Sample Output
3

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