# The Almost Lucky Numbers

## 题目描述

A lucky number is a number whose decimal representation contains only the digits $4$ and $7$. An almost lucky number is a number that is divisible by a lucky number.
For example, $14, 36$ and $747$ are almost lucky, but $2$ and $17$ are not. Note that a number can be both lucky and almost lucky at the same time (for example, $747$).
You are given long longs $a$ and $b$. Return the number of almost lucky numbers between $a$ and $b$, inclusive.

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