n=gets.chomp.to_i
arr=[]
n.times{
	l=gets.chomp.split(" ").map{|e| e.to_i}
	arr<<l
}
dp=[]
30.times{
	dp<<{}
}
dp[0][0]=0
(n/2).times{|i|
	now1=i*2
	next1=i*2+2
	dp[now1].collect{|k1,v1|
		for j in i..(n-1) do
			u1=(1<<j)
			if (k1 & u1)!=0 then
				next
			end
			for k in (i+1)..(n-1) do
				u2=(1<<k)
			
				if (k1 & u2)!=0 then
					next
				end
				k2=(k1|u1)|u2
				v2=v1+arr[j][k]
				if dp[next1].has_key?(k2)==false then
					dp[next1][k2]=v2
				elsif dp[next1][k2]<v2 then
					dp[next1][k2]=v2
				end
			end
			break
		end
	}
}
ans=0
dp[n].collect{|k,v|
	if ans<v then
		ans=v
	end
}
p ans