TypeError: unsupported operand type(s) for -: 'str' and 'str'

[Balaji]

import os
import pandas as pd
import numpy as np
import matplotlib as mlt
import csv


os.chdir("F:\Data Science\python program")


df=pd.read_csv("IMDB_data.csv",encoding='cp1252',skiprows=[2])


IMDB_Genre= df['Genre'].value_counts().to_frame().T


df.sort_values("Genre", axis = 0, ascending = True, 
                 inplace = True, na_position ='last') 


df['imdbRating']=pd.to_numeric(df['imdbRating'], errors='ignore',downcast='integer')
df['imdbVotes']=pd.to_numeric(df['imdbVotes'], errors='ignore',downcast='integer')


df['imdbVotes']=pd.to_numeric(df['imdbVotes'], errors='ignore',downcast='integer')

Error:
*​---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-9-b8c9307b8a6b> in <module>
----> 1 df['dif_and_sq']=int(df['imdbRating']).sub(int(df['imdbVotes']))
C:\ProgramData\Anaconda3\lib\site-packages\pandas\core\series.py in wrapper(self)
     91             return converter(self.iloc[0])
     92         raise TypeError("cannot convert the series to "
---> 93                         "{0}".format(str(converter)))
     94 
     95     wrapper.__name__ = "__{name}__".format(name=converter.__name__)
TypeError: cannot convert the series to <class 'int'>*


df['dif_and_sq']=df['imdbRating'].values-df['imdbVotes'].values
*---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-16-00740a4575a9> in <module>
----> 1 df['dif_and_sq']=df['imdbRating'].values-df['imdbVotes'].values
TypeError: unsupported operand type(s) for -: 'str' and 'str'