class Physical
  def initialize
    @v = []
    while v = $stdin.gets
      @v << v.chomp.to_f
    end
    calc
  end

  def calc
    @v.each do |v|
      t = v / 9.8
      y = 4.9 * t * t
      puts floor_check(y)
    end
  end

  def floor_check(y)
    f = 1
    while y > f * 5 - 5
      f += 1
    end
    return f
  end
end

p = Physical.new