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A8346 | $Lucky Sum$

时间限制1s

内存限制256MB

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题目描述

Petya loves lucky numbers. Everybody knows that lucky numbers are positive integers whose decimal representation contains only the lucky digits 4 and 7. For example, numbers 47, 744, 4 are lucky and 5, 17, 467 are not. Let $next(x)$ be the minimum lucky number which is larger than or equals $x$ . Petya is interested what is the value of the expression $next(l)+next(l+1)+...+next(r-1)+next(r)$ . Help him solve this problem.

输入格式

The single line contains two integers $l$ and $r$ ( $1<=l<=r<=10^{9}$ ) — the left and right interval limits.

输出格式

In the single line print the only number — the sum $next(l)+next(l+1)+...+next(r-1)+next(r)$ . Please do not use the %lld specificator to read or write 64-bit integers in C++. It is preferred to use the cin, cout streams or the %I64d specificator.

输入输出样例

输入 #1

2 7

输出 #1

输入 #2

7 7

输出 #2

C++ 编辑器

输入

输出