This program counts pairs of characters in batches of NMax and outputs the NOut top pairs with their counts.

NMax: the number characters that the i/o take from file each time.
NOut: the number of pairs to print sorted from high to low count.
============================================
INPUT:
Characters


============================================
OUTPUT:

("char1", "char2")		"count"
	.						.
	.						.
	.						.
	.						.
	.						.
	.						.
	.						.
	

#.###### seconds elapsed to finish the job.
===========================================

SAMPLE ON FILE:
File: Great Expectations
Source: Gutenburg project
Charecters count: 	More than 992924
Time elapsed to finish counting pairs: 0.035940 seconds 
NMax = 1
NOut = 20

========== OUTPUT FROM PROGRAM ===========
(e, )  26776     
( ,t)  22480     
(d, )  20251     
(t,h)  19756     
( ,a)  19204     
(h,e)  19078     
(t, )  16954     
(,, )  14475     
(i,n)  14142     
(e,r)  13291     
(s, )  13246     
(a,n)  12766     
( ,h)  12469     
( ,w)  12128     
( ,s)  11278     
(n,d)  10869     
(n, )  10783     
(h,a)  10057     
( ,o)  9976      
(r,e)  9793      

0.035940 seconds elapsed to finish the job.
===========================================

==== output with different NMax sizes =====
NMax = 1
Time = 0.035940 seconds
-----------------------
NMax = 10
Time = 0.035686 seconds
-----------------------
NMax = 1000
Time = 0.028271 seconds
-----------------------
NMax = 100000
Time = 0.029047 seconds
-----------------------
NMax = 1000000
Time = 0.029768 seconds