14091409 SUSTech Online Judge
Problem 1409 --Morse Code

1409: Morse Code

Time Limit: 1 Sec  Memory Limit: 128 MB
Submit: 203  Solved: 104
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Description

Pisces discovered a piece of Morse code. When he translated the Morse code into English, he still did not understand the meaning of translated message. After several days of hardworking, he finally discovered that the passage was encrypted using a "fence transposition" method. The so-called "fence transposition" method is to truncate the letters in the ciphertext into two lines of the same length and then insert the letters of the second line into the first line in turn to obtain the plaintext. For example, we have a ciphertext "ACEBDF". We cut it in half, then we get "ACE" in the first line, "BDF" in the second line. We then insert "B" between "A" and "C", "D" between "C" and "E", and so on. After insertion, we get plaintext "ABCDEF". Now, Pisces gives you the original Morse code. Please find the plaintext for him. 

Input

The first line contains a single integer \(T (1\leq T\leq 100)\), which represents the number of test cases.  
Each test case has two lines. The first line contains an even integer \(n(20\leq n\leq 1000)\), representing the number of characters. Only uppercase English letters and digits will appear after translation. The second line contains \(n\) space-seperated strings, representing the original Morse code.

Output

For each test case, print the plaintext.

Sample Input

1
20
.... .--. -.-- .. - -.. -.-- ..- - -.-. .- .--. -... .-. .... .- ... ... . ....

Sample Output

HAPPYBIRTHDAYSUSTECH

HINT

Source

 

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