Problem:
Score : 300 points

Problem Statement

You are given an integer N. Among the integers between 1 and N (inclusive), how many Shichi-Go-San numbers (literally "Seven-Five-Three numbers") are there?

Here, a Shichi-Go-San number is a positive integer that satisfies the following condition:

When the number is written in base ten, each of the digits 7, 5 and 3 appears at least once, and the other digits never appear.

Constraints

1 \leq N < 10^9

N is an integer.

Input

Input is given from Standard Input in the following format:

N

Output

Print the number of the Shichi-Go-San numbers between 1 and N (inclusive).

Sample Input 1

575

Sample Output 1

4

There are four Shichi-Go-San numbers not greater than 575: 357, 375, 537 and 573.

Sample Input 2

3600

Sample Output 2

13

There are 13 Shichi-Go-San numbers not greater than 3600: the above four numbers, 735, 753, 3357, 3375, 3537, 3557, 3573, 3575 and 3577.

Sample Input 3

999999999

Sample Output 3

26484

Solution in Lua (5.3.2) (judge verdict: Accepted)

local TernaryCounter = {}

function TernaryCounter.new()
    local self = setmetatable({}, {__index = TernaryCounter})
    self.count = {0}
    return self
end

function TernaryCounter:inc()
    local t = self.count
    local digits = #t
    t[1] = t[1] + 1
    for i=1,digits do
        if t[i] == 3 then
            t[i] = 0
            if t[i+1] == nil then
                t[i+1] = 0
            else
                t[i+1] = t[i+1] + 1
            end
        end
    end
    return self
end

function TernaryCounter:tonumber()
    local dic = {[0]=3, [1]=5, [2]=7}
    local t = self.count
    local ans = 0
    for i=#t,1,-1 do
        ans = ans * 10 + dic[t[i]]
    end
    return ans
end

function TernaryCounter:is753()
    local oc = {[0]=0, [1]=0, [2]=0}
    for _,v in ipairs(self.count) do
        oc[v] = oc[v] + 1
        if oc[0] > 0 and oc[1] > 0 and oc[2] > 0 then
            return true
        end
    end
    return false
end

local N = io.read("n")

local cntr = TernaryCounter.new()
local ans = 0
while true do
    local n = cntr:tonumber()
    if n > N then
        break
    end
    if cntr:is753() then
        ans = ans + 1
    end
    cntr:inc()
end
print(ans)