#!/usr/bin/perl
use strict;
use warnings;
my $n =($ARGV[0] || 8);
# usage : perl queens.pl n
# ex : perl queens.pl 20
#############
my $p=1;
my (@s,@r);
my $str;
my $re='_(\d+)!';
for my $i (1..$n) {
    for my $j (1..$n) {
        $str.= join '!',"_$j",(map {join';',$j-$_<0?0:$j-$_,$j+$_ >$n?0:$j+$_} (1..($n-$i))),'';
    }
    $str.="\n";
    push @s,$p+1,$p+2;
    push @r,$p;
    $re.=($i==$n)?'':(('(\d+);(\d+)!'x($n-$i)).".*?\n.*?_(?!(?:\\".(join '|\\',@r,@s).')!)(\d+)!');
    $p+=2*($n-$i)+1;
    $_+=2 for @s;
}
my $l="a";
if ($str=~$re){print join",",map{$l++.eval"\$$_"}@r} else {print "no solution"}
#print "\n\n",$str;
#print "\n\n",$re;