use warnings;
use strict;

my $line;

while (<DATA>) {
    my $part = (split)[0];
    if (/[.()]/) {
        $line =~ s/\s*$//;
        $line .= $part;
    }
    else {
        $line .= $part . q[ ];
    }
}

print $line;

__DATA__ 
i o
am  o
2  o
(  o
but o
)  o
.  o
how o