Remove First N-1 Zeros From Pandas Dataframe Column

df_in is the sample dataframe and df_out is the expected output.

How do I remove the first 5 zeros so that I have one zero and all other elements.

import pandas as pd

df_in = pd.DataFrame({'a':[0,0,0,0,0,0,1,2]})

df_out=pd.DataFrame({'a':[0,1,2]})

Thanks in advance.

find the value and remove duplicates then concat with others

pd.concat([df_in.loc[df_in.a == 0, :].drop_duplicates(), df_in.loc[df_in.a != 0,:]])