Divisible and Non-divisible Sums Difference

Easy

You receive positive integers n and m.

Define two integers as follows:

num1: The sum of all integers in the range [1, n] (both inclusive ) that are not divisible by m.
num2: The sum of all integers in the range [1, n] (both inclusive ) that are divisible by m.

Find and provide the integer num1 - num2.

Example 1

Input: n = 10, m = 3

Output: 19

Explanation: In the given example:

Integers in the range [1, 10] that are not divisible by 3 are [1,2,4,5,7,8,10], num1 is the sum of those integers = 37.
Integers in the range [1, 10] that are divisible by 3 are [3,6,9], num2 is the sum of those integers = 18.

We provide 37 - 18 = 19 as the answer.

Example 2

Input: n = 5, m = 6

Output: 15

Explanation: In the given example:

Integers in the range [1, 5] that are not divisible by 6 are [1,2,3,4,5], num1 is the sum of those integers = 15.
Integers in the range [1, 5] that are divisible by 6 are [], num2 is the sum of those integers = 0.

We provide 15 - 0 = 15 as the answer.

Example 3

Input: n = 5, m = 1

Output: -15

Explanation: In the given example:

Integers in the range [1, 5] that are not divisible by 1 are [], num1 is the sum of those integers = 0.
Integers in the range [1, 5] that are divisible by 1 are [1,2,3,4,5], num2 is the sum of those integers = 15.

We provide 0 - 15 = -15 as the answer.

Constraints

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