- Time limit:
- 3000 ms
- Memory limit:
- 128 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 28 is perfect because 28 = 1 + 2 + 4 + 7 + 14.

Motivated by this definition, we introduce the metric of **imperfection **of number *N*, denoted with *f**(**N**)*, as the absolute difference between *N *and the sum of its divisors less than *N*. It follows that perfect numbers’ imperfection score is 0, and the rest of natural numbers have a higher imperfection score. For example:

- f(6) = |6 - 1 - 2 - 3| = 0,
- f(11) = |11 - 1| = 10,
- f(24) = |24 - 1 - 2 - 3 - 4 - 6 - 8 - 12| = |-12| = 12.

Write a programme that, for positive integers *A** *and *B,** *calculates the sum of imperfections of all numbers between *A *and *B*: *f**(**A**) + **f**(**A **+ **1**) + ... + **f**(**B**)*.

The first line of input contains the positive integers *A *and *B *(1 ≤ *A *≤ *B *≤ 10^{7}).

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

**Editor: **

**Source: **
Croatian Open Competition in Informatics 2016/2017, contest 6 (COCI 2016 #6)

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