Hacker rank Strong Password

#!/bin/python3
 
import math
import os
import random
import re
import sys
 
#
# Complete the 'minimumNumber' function below.
#
# The function is expected to return an INTEGER.
# The function accepts following parameters:
#  1. INTEGER n
#  2. STRING password
#
 
def minimumNumber(n, password):
    # Return the minimum number of characters to make the password strong
    numbers = "0123456789"
    lower_case = "abcdefghijklmnopqrstuvwxyz"
    upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    special_characters = "!@#$%^&*()-+"
    isnum,islower,isupper,isspecial=0,0,0,0
    for i in password:
        if i in numbers: isnum=1
        if i in lower_case: islower=1
        if i in upper_case: isupper=1
        if i in special_characters: isspecial=1
    cnt=len(password)
    isSum=4-(isnum+islower+isupper+isspecial)
    if isSum+cnt<6: return 6-(isSum+cnt)+isSum
    else :return isSum
    
if __name__ == '__main__':
    fptr = open(os.environ['OUTPUT_PATH'], 'w')
 
    n = int(input().strip())
 
    password = input()
 
    answer = minimumNumber(n, password)
 
    fptr.write(str(answer) + '\n')
 
    fptr.close()