import pandas as pd
def valid_emails(users: pd.DataFrame) -> pd.DataFrame:
result=users[users['mail'].str.match(r'^[A-Za-z][A-Za-z0-9_\.\-]*@leetcode\.com$')]
return result
# Write your MySQL query statement below
select * from Users
where mail regexp '^[A-Za-z][A-Za-z0-9_\.\-]*@leetcode(\\?com)?\\.com$'