执行如下 Python 程序， 运行的结果是？ （ ）

def zfzh(s):

        c = ''

        for ch in s:

                if "9">=ch>= "0":

                        c+=str(int(ch)+1)

                elif "z">=ch>= "a":

                        c+= chr(ord(ch)- ord("a")+ord("A"))

        return c

s = 'hzag-21-8'

print(zfzh(s))