a1	b1	c1	d1
a2	b2	c2	d2
a3	b3	c3	d3
a4	b4	c4	d4

##</code><code>##

#!/usr/bin/perl
open (datafile, "file_A.txt");
@fileinput = split("\t", <datafile>);
    
for ($i = 2; $i <=200;){
    open(OF, "file_B.txt"); #file_B.txt contains the original file 
    open(NF, ">file_B_out.txt"); #file_B_out.txt contains the processed output
    while ($line = <OF>) {
    print "$fileinput[$i]\n";
    print "$i\n";
    $line =~ s/$fileinput[$i]/$fileinput[$i+1]/g;
    #print $line;
    print NF $line;
    
    }
$i=$i+4;
}
close(NF);
close(OF);