3469. Savrsen

单测试点时限: 3.0 秒

内存限制: 256 MB

A number is perfect if it is equal to the sum of its divisors, the ones that are smaller than it. For example, number is perfect because .

Motivated by this definition, we introduce the metric of imperfection of number , denoted with , as the absolute difference between and the sum of its divisors less than . It follows that perfect numbers’ imperfection score is , and the rest of natural numbers have a higher imperfection score. For example:

  • ,
  • ,
  • .

Write a programme that, for positive integers and , calculates the sum of imperfections of all numbers between and : .

输入

The first line of input contains the positive integers and ().

输出

The first and only line of output must contain the required sum.

样例

Input
24 24
Output
12
Input
1 9
Output
21

提示

Clarification of the first test case: .

25 人解决,35 已尝试。

50 份提交通过,共有 146 份提交。

8.1 EMB 奖励。

创建: 1 年前.

修改: 12 月前.

最后提交: 4 月,3 周前.

来源: COCI 2017

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