N = gets.to_i
S = (1 << N)
DP = Array.new(S,-1)
DP[0] = 0
U = N.times.map{ gets.split.map(&:to_i) }

def make_unit(s)
  if DP[s] < 0
    N.times do |i|
      N.times do |j|
          if i > j && (s & 1 << i) > 0 && (s & 1 << j) > 0
              ex = (1 << i) | (1 << j)
              like = make_unit(s ^ ex) + U[i][j]
              if like > DP[s]
                  DP[s] = like
              end
          end
      end
    end
  end
  return DP[s]
end

make_unit(S-1)
puts DP[S-1]