输入某年某月某日，判断这一天是这一年的第几天？　1.程序分析：以3月5日为例，应该先把前两个月的加起来，然后再加上5天即本年的第几天，特殊　　　　情况，闰年且输入月份大于3时需考虑多加一天。(What is the day of the year? 1. program analysis: taking March 5th as an example, we should first add up the first two months, and then add 5 days, that is, the first few days of the year. When considering the special case, leap year and input month is more than 3, we need to consider adding one more day.)