while ( <FB> ){
    chomp; 
    my($col0, $col1, $col2, $col3) = split ","; 
    push @B, [$col0, $col1, $col2, $col3];

}

##</code><code>##

file706,010390010010,doc_01,paragraph,11
file707,010390010010,doc_01,paragraph,12
file708,010390010010,doc_01,paragraph,09
file710,010390010010,doc_01,paragraph,10
file711,010390010010,doc_01,paragraph,13
file712,010390010010,doc_01,paragraph,11
file713,010390010010,doc_01,paragraph,12
file714,010390010010,doc_01,paragraph,09
file715,010390010010,doc_01,paragraph,10
file716,010390010010,doc_01,paragraph,13
file717,010390010010,doc_01,paragraph,11
file718,010390010010,doc_01,paragraph,12
file719,010390010010,doc_01,paragraph,09
file720,010390010010,doc_01,paragraph,10
file721,010390010010,doc_01,paragraph,11
file722,010390010010,doc_01,paragraph,12
file723,010390010010,doc_01,paragraph,11
file725,010390010010,doc_01,paragraph,12
file726,010390010010,doc_01,paragraph,11
file727,010390010010,doc_01,paragraph,12
file728,010390010010,doc_01,paragraph,11
file729,010390010010,doc_01,paragraph,12
file730,010390010010,doc_01,paragraph,12