file size: 70GB
file format :  tsv

1     34
2     6
3     78

simple while-loop time:  

real	10m51.378s
user	9m22.610s
sys	0m13.120s



while loop with regex + push and shift + one subtraction(i forgot to mention that)

real	157m13.245s
user	152m8.520s
sys	1m26.660s