编写一个程序，只要输入年月日，就能回答那天是星期几。

输入一个日期，包括年、月、日。(一组测试数据)

输出这个日期是星期几。-Write a program, just enter the year, month day, able to answer the day of the week. Enter a date, including year, month, day. (A set of test data) output for the day of the week.