hi try out this one

#!/usr/bin/perl
use strict;
print "Enter the txt\n";
my ($input,@ss,$i);
chop($input=<STDIN>);
open(FILE,"txt.txt") or die $!;
@ss=<FILE>;
close(FILE);
foreach $i(0 .. scalar @ss){
        if($ss[$i] =~ /$input/)
        {
                if($i ne 0){print "$ss[$i-1]";}
                print "$ss[$i]";
                print "$ss[$i+1]";
        }
}
[download]