@ARGV = glob 'datafile*';

open my $OUTPUT, '>', 'output_file' or die "Cannot open 'output_file' because: $!";

my %data;
while ( <> ) {
    next unless /^(.+) (\S+)$/;
    push @{ $data{ $1 } }, $2;
    }

for my $key ( sort keys %data ) {
    print join ' ', $key, @{ $data{ $key } }, scalar @{ $data{ $key } }, "columns\n";
    }