Thank you all for the comments.

So what I want is, only consider those lines which have a value greater than 4 in the 2 column.

#########
109027 28
109028 30
116958 15
116960 35
116961 39
116962 70
116963 72
147184 2
147588 1
153087 32
########
in this set
109028 - 109027 is not greater 50
116958 - 109028 is greater than 50

so I take
109027 109078(109028 + 50)
so the next one will start from 116958
similiarly like above
153087 - 116963 > 50
so
116958 117013 (which is 116963 + 50)
Since 153087 did not have any neighbours.
153087 153137

i hope that will make a little bit more sense.
I am sorry guys for a vague explanation..
Thank you in advance,
Deepak