Back in the roman empire, a cipher was used to exchange secret message between Cesar and his centurions. The goal of this puzzle is to write a decoder for this cipher.

The encryption consists in taking a message, for example "Ave and Welcomus to Coderus Charti" and a number of columns, for example 5.

The encryption is performed in 3 phases.

In phase 1: the message is written vertically on the columns. For the last column, if the message ends before the last row, it is completed with dots (.). For the previous message, the phase 1 would look like this:

A uoC
vWsdh
ee ea
 ltrr
acout
no si
dmC .

In phase 2: the even rows (2,4,...) are reversed. The phase 2 processing looks like this:

A uoC
hdsWv
ee ea
rrtl
acout
is on
dmC .

In phase 3: the rows are concatenated to form a string, the final encrypted message thus looks like this:

A uoChdsWvee earrtl acoutis ondmC .

Input Specifications

The input file contains two lines:

1. the number c of columns
2. the encrypted message

For example:

5
A uoChdsWvee earrtl acoutis ondmC .

Output Specifications

The output result must be printed on the standard output. The result to be printed is the decoded message. The extra padding dots (.) must not be removed.

So for the previous example, the output should be:

Ave and Welcomus to Coderus Charti.