#!/usr/bin/perl
use strict;
use warnings;
use 5.10.0;

my %count;

while (<DATA>) {
    if (/^(\S+)\s+([A-Z])$/) {
        $count{$1}{$2}++;
    } else {
        warn "Regular expression failed on $_";
    }
}

for my $name (sort keys %count) {
    if (exists $count{$name}{Z}) {
        say "$name $count{$name}{Z}"
    }
}

__DATA__
Tommy Z
Tommy Z
Chris Z
Chris B
Chris Z
Jake Z
Jake Y

##</code><code>##

#!/usr/bin/perl
use strict;
use warnings;
use 5.10.0;

my $count;
while (<DATA>) {
    $count++
}
say $count;