1)There are 13572668 lines in file 1 and 27145336
lines in file2. [with the grep function - the 
number of sequences in file1 is 6786334 and 
file2 is 13572668]

2)Both the file have a set of unique ids. So, 
file2 is double the number of id's(for left 
and right) compared to file1. 

3)The size of the file1 is 8GB and file2 is 2GB. 

4)The sequences appear in the sorted order for 
both the files. therefore, the first id in file1 
and the first 2 id's(one for left, one for right) 
of file2 will be the same.