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# Number of Days Between Two Dates

[題目](https://leetcode.com/problems/number-of-days-between-two-dates/)

{% embed url="<https://leetcode.com/problems/number-of-days-between-two-dates/>" %}

Write a program to count the number of days between two dates.

The two dates are given as strings, their format is `YYYY-MM-DD` as shown in the examples.

**Example 1:**

```
Input: date1 = "2019-06-29", date2 = "2019-06-30"
Output: 1
```

**Example 2:**

```
Input: date1 = "2020-01-15", date2 = "2019-12-31"
Output: 15
```

**Constraints:**

* The given dates are valid dates between the years `1971` and `2100`.