#encoding:utf-8 No.0024 2014.10.2
min_v = []
while true
  v = gets.chomp
  if v == ""
    break
  end
  min_v.push v.to_f
end

min_v.length.times do |i|
  n = 1
  while true
    x = (5*n-5)/4.9
    if min_v[i] <= 9.8 * Math.sqrt(x)
      puts n
      break
    end
    n += 1
  end
end