use strict;
use warnings;

sub divisible_by_3 {
    my $num = shift;
    while (length($num) > 1) {
        my $sum = 0;
        map { $sum += $_ } split '', $num;
        $num = $sum;
    }
    return $num =~ /^[0369]$/;
}

sub divisible_by_5 {
    my $num = shift;
    return ($num =~ /[05]$/);
}

sub divisible_by_15 {
    my $num = shift;
    return (divisible_by_3($num) and divisible_by_5($num));
}

foreach (1 .. 100) {
    printf "%s\n",
        divisible_by_15($_)? "fizzbuzz":
        divisible_by_3($_)?  "fizz":
        divisible_by_5($_)?  "buzz":
        $_;
}