#方針: 753数を全列挙
 
def is_753?(s)
  f7=f5=f3 = false
  s.chars do |c|
    case c
    when "7"
      f7=true
    when "5"
      f5=true
    when "3"
      f3=true
    end
  end
  return f7&&f5&&f3
end
 
list = ["7","5","3"]
ary = []
(3..9).each do |digit|
  (0..3**digit-1).each do |bit|
    tmp = ""
    (0..digit-1).each do |i|
      tmp += list[bit.to_s(3).rjust(digit,"0")[i].to_i]
    end
    ary << tmp if is_753?(tmp)
  end
end
 
n = gets.to_i
 
ans = 0
ary.each_with_index do |a, i|
  if a.to_i <= n
    ans+=1
  end
end
 
p ans