用javs,Python回答下雨问题

Question

八月份，一个省份有三个地区分别下了20，17，15天的雨，三个地区同时有七天下雨，又有两个地区10天在下雨，请问一共有几天没下雨

Answer 1

a = 20
b = 17
c = 15
d = [a,b,c]
day = 0
for i in d:
  if d>= 7+10:
    day += (i-17)
  else:
    day += (i-7)
print(31-day-7-10)
# 答案是3