How can one join the shortest and longest strings of different text files?

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A
,AA
...
,AAAA
,AAAAA
,

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T
,TT
...
,TTTT
,TTTTT
,

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G
,GG
...
,GGGG
,GGGGG
,

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#!/usr/bin/perl  
use warnings;  
...
 
exit; 
########################################

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Microsoft Windows [Version 6.1.7601]
Copyright (c) 2009 Microsoft Corporation.  All rights reserved.
...
 Length 4.0; Seq: GGGG

######## File 3 ends ##############

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Two shortest strings (small to big): 
 Seq 1: ATG
...
Two longest strings (big to small):
 seq 1: AAAAATTTTTGGGGG 
 seq 2: AAAATTTTGGGG

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