use strict;
use warnings;

my @fields = (
    'abc abc1 abc2',
    'abc abc1 abc3 abc5',
    'abc2 abc3 abc5 abc7 abc9 abc10',
    'abc1 abc2 abc3 abc4 abc5 abc6',
    );

print grep {length > 15} map {s/\s+//g; "$_\n"} @fields;

##</code><code>##

abcabc1abc3abc5
abc2abc3abc5abc7abc9abc10
abc1abc2abc3abc4abc5abc6