TOANDFRO - To and Fro

Mo and Larry have devised a way of encrypting messages. They first decide secretly on the number of columns and write the message (letters only) down the columns, padding with extra random letters so as to make a rectangular array of letters. For example, if the message is “There’s no place like home on a snowy night” and there are five columns, Mo would write down

t o i o y
h p k n n
e l e a i
r a h s g
e c o n h
s e m o t
n l e w x

Note that Mo includes only letters and writes them all in lower case. In this example, Mo used the character ‘x’ to pad the message out to make a rectangle, although he could have used any letter. Mo then sends the message to Larry by writing the letters in each row, alternating left-to-right and right-to-left. So, the above would be encrypted as

toioynnkpheleaigshareconhtomesnlewx

Your job is to recover for Larry the original message (along with any extra padding letters) from the encrypted one.

Input

There will be multiple input sets. Input for each set will consist of two lines. The first line will contain an integer in the range 2...20 indicating the number of columns used. The next line is a string of up to 200 lower case letters. The last input set is followed by a line containing a single 0, indicating end of input.

Output

Each input set should generate one line of output, giving the original plaintext message, with no spaces.

Example

Input:
5
toioynnkpheleaigshareconhtomesnlewx
3
ttyohhieneesiaabss
0

Output:
theresnoplacelikehomeonasnowynightx
thisistheeasyoneab

Added by:Adrian Kuegel
Date:2005-07-09
Time limit:1s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All
Resource: ACM East Central North America Regional Programming Contest 2004

hide comments
2014-07-14 09:12:10 chin
silly mistakes costed lots of WAs!!...
easy one !!!
2014-06-28 10:36:06 codecode
I have done this in single for loop in O(n) @pavanym
2014-06-24 21:23:55 Amitrajit Chattopadhyay
is there any case when the number of letters is not divisible by the number of columns?
2014-06-18 23:22:26 Damn
i am getting a wrong answer. but i am getting the correct output on ideone. can someone see whats wrong <snip>

Last edit: 2023-05-19 23:51:27
2014-03-20 05:54:29 Norman Fernandez
Got AC after WA with same code with same results...
2014-03-11 14:01:44 SegF4ult
Can't seem to get AC using Py2.7, did a diff using output of a Java attempt with my Python output.. No difference, so why no pass?
2014-02-05 12:19:45 RAJAT SINGH
got AC in second attempt.........but first one also giving correct ans codeblocks but i don't know why it is wrong in spoj compiler
2013-11-12 11:15:28 Rahul Jain
I have done 2 problem worth of 0.02 and 0.01 points but I didn't get any point ..Why??
On solving this problem too, I didn't get any points.

Last edit: 2013-11-12 11:27:56
2013-11-02 08:52:14 Shubham Goyal
can anyone please tell me what's wrong with this code....please....
http://www.spoj.com/submit/TOANDFRO/id=10402254

Last edit: 2013-11-02 08:53:03
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