sub ruler {
    my $n = 9 + shift; chop $n;
    join "", " ", map(" "x(9-/../).$_, 1..$n), "\n",
    "0123456789" x $n, "0\n"
}

##</code><code>##

sub ruler {
    my $n = shift;
    join"", " ", map(" "x(9-/../).$_, 1..$n/10), "\n",
    map(/.$/g, 0..$n), "\n"
}

##</code><code>##

perl -lwe 'print" ",map(" "x(9-/../).$_,1..$ARGV[0]/10),"\n",map/.$/g,0..shift'