# 0878. Nth Magical Number

<https://leetcode.com/problems/nth-magical-number>

## Description

A positive integer is *magical* if it is divisible by either `a` or `b`.

Given the three integers `n`, `a`, and `b`, return the `nth` magical number. Since the answer may be very large, **return it modulo** `109 + 7`.

**Example 1:**

```
**Input:** n = 1, a = 2, b = 3
**Output:** 2
```

**Example 2:**

```
**Input:** n = 4, a = 2, b = 3
**Output:** 6
```

**Example 3:**

```
**Input:** n = 5, a = 2, b = 4
**Output:** 10
```

**Example 4:**

```
**Input:** n = 3, a = 6, b = 4
**Output:** 8
```

**Constraints:**

* `1 <= n <= 109`
* `2 <= a, b <= 4 * 104`

## ac

```java
```