使用python程序判断年月日问题

#输入某年某月某日，判断这一天是这一年的第几天？
year = int(input("年:"))
month = int(input("月:"))
day = int(input("日:"))
months = [0,31,28,31,30,31,30,31,31,30,31,30,31]
if year%400 == 0 or year%4 == 0:
   months[3] = months[3] + 1
if 0 <month<= 12:
   days = 0
   for item in range (month):
       sum = months[item]
       days = days +sum
   day_s=days + day
   print(f'今天是今年的第{day_s}天')
else:
   print('输入日期超出范围')