import string

inputIBAN = 'DE520000418'


LETTERS_DICT={}
for i,d in enumerate(string.digits + string.ascii_uppercase):
    LETTERS_DICT[ord(d)] = str(i)



def iban_letter_replacement(iban_string):
    
    iban_numeric = iban_string.translate(LETTERS_DICT)

    return iban_numeric

def iban_valid(iban_string):
    inverted_iban = iban_string[4:] + iban_string[:4]
    inverted_numeric = int(iban_letter_replacement(inverted_iban))
    return (inverted_numeric % 97) ==1


def iban_char_verify(iban_string):
    iban_nc =  iban_string[4:] + iban_string[:2] + '00' 

    iban_nc_inv_num = int(iban_letter_replacement(iban_nc))

    return '{:02}'.format(98 - iban_nc_inv_num % 97)==iban_string[2:4]
    

def check_iban(iban_string):
    return iban_char_verify(iban_string) and iban_valid(iban_string)

print(check_iban(inputIBAN))