n = gets.to_i
a = Array.new
max_c = "1"
n.times do
    s = gets
    s.each_char do |x|
        max_c = x if x.ord > max_c.ord
    end
    a.push(s)
end
base = 2
if max_c.ord >= "1".ord && max_c.ord <= "9".ord
    base = max_c.ord - 48 + 1
else
    base = max_c.ord - 55 + 1
end
min = 10 ** 50
a.each do |x|
    b = x.to_i(base)
    min = b if b < min
end
puts min