n = gets.to_i
a = []
for i in 1..n
	a.push(gets.to_s)
end

t = 0
dic = {}
for s in "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ".chars
	dic[s] = t
	t += 1
end

ar = []
for i in 0..n-1
	ar.push(a[i].to_i(dic[a[i].chars.max]+1))
end
puts ar.min