Python输入某年某月某日，判断这一天是这一年的第几天？

while 1:
    year = int(input('year:n'))      #输入年、月、日
    month = int(input('month:n'))
    day = int(input('day:n'))

    months = (0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334)   #把每月的前几个月的天数加起来
    if 0 < month <= 12 and day <= 31:
        sum = months[month - 1]
        sum += day
        leap = 0
        if (year % 400 == 0) or ((year % 4 == 0) and (year % 100 != 0)):  #判断是否为闰年
            leap = 1
        if (leap == 1) and (month > 2):
            sum += 1
        print('这是%s年的第%s天' % (year, sum))
        break
    else:
        print('输入错误,请重新输入！n')