如何将字符串中的数字跟字母分开

import sys
# coding=utf-8
stringg='11AABBCCbc22defghijklm'
sz=[]
zm=[]
for i  in stringg:
    i=i.lower() #1122aabbcdefghijklm
    if i in  "abcdefgfhijklmopq": #abcdefgfhijklm
        zm.append(i)

    if i in '0123456789':
        sz.append(i)
print(sz) #1122
print(zm) #abcdefgfhijklm