N = gets.to_i
$chemistory = {}
N.times.each{|y|
  gets.split.take(N).map(&:to_i).each_with_index{|v, x|
    $chemistory[[x,y]] = v
  }
}

$dp={}
def g(unused)
  $dp[unused] ||= if unused.empty?
    0
  else
    a = unused.first
    (unused - [a]).inject(0){|r,b|
      [r, $chemistory[[a,b]] + g(unused - [a, b])].max
    }
  end
end

p g([*0...N])