python 求s=a+aa+aaa+aaaa+aa...a的值

#!/usr/bin/python
# -*- coding: UTF-8 -*-

a = int(input("a："))
b = int(input("b："))
s = []
t = 0
for i in range(0 , b):
    t = t + a
    a = a * 10
    s.append(t)
    # print(t)

s = sum(s)
print(s)