Unsupported operand error for datetime values

I am getting the following error when running the code below:

prev_suffix = ('_' + current_year + '_q' + str(int(current_quarter) - 2))
      8 elif cq == '1':
----> 9     prev_suffix = ('_' + current_year -1 + '_q' + str(int(current_quarter) + 2))

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

Not entirely sure why this is not working

x = datetime.datetime.now()
current_year = str(x.year)[2:]
current_quarter = str(((x.month-1)//3)+1)
current_suffix = ('_' + current_year + '_q' + current_quarter)

if current_quarter == '3':
        prev_suffix = ('_' + current_year + '_q' + str(int(current_quarter) - 2))
elif cq == '1':
    prev_suffix = ('_' + current_year -1 + '_q' + str(int(current_quarter) + 2))

>Solution :

It is because of

current_year -1 

It should be

str(int(current_year) - 1))

This being the final version:

x = datetime.datetime.now()

current_year = str(x.year)[2:]
current_quarter = str(((x.month-1)//3)+1)
current_suffix = ('_' + current_year + '_q' + current_quarter)

if current_quarter == '3':
        prev_suffix = ('_' + current_year + '_q' + str(int(current_quarter) - 2))
elif current_quarter == '1':
    print(type(current_year), type(current_quarter))
    prev_suffix = ('_' + str(int(current_year) - 1) + '_q' + str(int(current_quarter) + 2))