<p>Write a program to count the number of days between two dates.</p>

<p>The two dates are given as strings, their format is <code>YYYY-MM-DD</code>&nbsp;as shown in the examples.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<pre><strong>Input:</strong> date1 = "2019-06-29", date2 = "2019-06-30"
<strong>Output:</strong> 1
</pre><p><strong class="example">Example 2:</strong></p>
<pre><strong>Input:</strong> date1 = "2020-01-15", date2 = "2019-12-31"
<strong>Output:</strong> 15
</pre>
<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li>The given dates are valid&nbsp;dates between the years <code>1971</code> and <code>2100</code>.</li>
</ul>

class Solution:
    def daysBetweenDates(self, date1: str, date2: str) -> int:
        def f(date):
            y,m,d=map(int,date.split('-'))
            if m<3:
                m+=12
                y-=1
            return 365*y+y//4+y//400-y//100+d+(153*m+8)//5
        return abs(f(date1)-f(date2))





        
16400