2240\. Number of Ways to Buy Pens and Pencils

Medium

You are given an integer `total` indicating the amount of money you have. You are also given two integers `cost1` and `cost2` indicating the price of a pen and pencil respectively. You can spend **part or all** of your money to buy multiple quantities (or none) of each kind of writing utensil.

Return _the **number of distinct ways** you can buy some number of pens and pencils._

**Example 1:**

**Input:** total = 20, cost1 = 10, cost2 = 5

**Output:** 9

**Explanation:** The price of a pen is 10 and the price of a pencil is 5. 

- If you buy 0 pens, you can buy 0, 1, 2, 3, or 4 pencils. 

- If you buy 1 pen, you can buy 0, 1, or 2 pencils. 

- If you buy 2 pens, you cannot buy any pencils. 
  
The total number of ways to buy pens and pencils is 5 + 3 + 1 = 9.

**Example 2:**

**Input:** total = 5, cost1 = 10, cost2 = 10

**Output:** 1

**Explanation:** The price of both pens and pencils are 10, which cost more than total, so you cannot buy any writing utensils. Therefore, there is only 1 way: buy 0 pens and 0 pencils.

**Constraints:**

*   <code>1 <= total, cost1, cost2 <= 10<sup>6</sup></code>