use strict;
use warnings;
# perl 5.10 only used for say() and infix //
use 5.010;

my $size = shift(@ARGV) // 6;
for my $turn (0.. ($size - 2)) {
    my @players;
    @players[0..($size-1)] = ((1) x $size);
    for (0 .. ($size / 2 - 1)) {
        my $current = $_;
        $current = ($current + 1) % $size until $players[$current];
        $players[$current] = 0;

        my $other = ($size - $turn - $current - 1) % $size;
        $other = ($other - 1) % $size until $players[$other];
        $players[$other] = 0;
        say $current + 1, '-', ($other + 1);
    }
    say '=' x 10;
}