Get the row(s) which have the max value in groups using groupby

How do I find all rows in a pandas DataFrame which have the max value for count column, after grouping by ['Sp','Mt'] columns?

Example 1: the following DataFrame:

   Sp   Mt Value   count
0  MM1  S1   a     **3**
1  MM1  S1   n       2
2  MM1  S3   cb    **5**
3  MM2  S3   mk    **8**
4  MM2  S4   bg    **10**
5  MM2  S4   dgd     1
6  MM4  S2   rd      2
7  MM4  S2   cb      2
8  MM4  S2   uyi   **7**

Expected output is to get the result rows whose count is max in each group, like this:

   Sp   Mt   Value  count
0  MM1  S1   a      **3**
2  MM1  S3   cb     **5**
3  MM2  S3   mk     **8**
4  MM2  S4   bg     **10** 
8  MM4  S2   uyi    **7**

Example 2:

   Sp   Mt   Value  count
4  MM2  S4   bg     10
5  MM2  S4   dgd    1
6  MM4  S2   rd     2
7  MM4  S2   cb     8
8  MM4  S2   uyi    8

Expected output:

   Sp   Mt   Value  count
4  MM2  S4   bg     10
7  MM4  S2   cb     8
8  MM4  S2   uyi    8