func main()
	var n: int :: cui@inputInt()
	var s: [][]char :: #[n][]char
	for i(0, n - 1)
		do s[i] :: cui@input()
	end for
	
	var ans: int :: n
	var num: int :: n * (n - 1) / 2
	for ii(0, 2 ^ num - 1)
		var id: int :: ii
		var cnt: []int :: #[n]int
		for i(0, n - 1)
			for j(i + 1, n - 1)
				var result: char :: "ox"[id % 2]
				do id :/ 2
				if(s[i][j] <> '-' & s[i][j] <> result)
					skip ii
				end if
				if(result = 'o')
					do cnt[i] :+ 1
				else
					do cnt[j] :+ 1
				end if
			end for
		end for
		var cnt0: int :: cnt[0]
		do cnt.sort()
		do cnt.reverse()
		var rank: int :: 1
		for i(0, n - 1)
			if(i <> 0 & cnt[i] <> cnt[i - 1])
				do rank :+ 1
			end if
			if(cnt[i] = cnt0)
				do ans :: [ans, rank].min()
				break i
			end if
		end for
	end for
	do cui@print("\{ans}\n")
end func