a, b, c = gets.split
d, e, f = gets.split
case b.size <=> e.size
when -1
  puts d
when 0
  (0...b.size).each do |i|
    case b[i] <=> e[i]
    when -1
      puts d
      break
    when 1
      puts a
      break
    end
    if i == b.size - 1
      puts -1
    end
  end
when 1
  puts a
end