### Day of the Week (Due 10 July 2011)

In this program you will prompt the user to enter the day, month, and year. Your program will print out the day of the week for that date. Here is a sample output for the program:
```Enter day: 12
Enter month: 12
Enter year: 1960

The day is Monday.

```

All the input values will be positive integers. The day will be in the range 1 through 31. The month will be in the range 1 through 12 where 1 is for January and 12 is for December. The year will be a four digit number in the range 1900 through 2100.

Your program will check the following:
• The day is in the range 1 and 31.

• The month is in the range 1 and 12.

• The year is between 1900 and 2100.
All the above limits are inclusive. If any one of the conditions fails then the program will keep prompting the user to enter that value. You will have to use a loop to achieve that. You need not check that the user has entered the correct day for a given month. For example, the user will not enter 31 for the day in the month of February.

This algorithm was developed by Rev. Zeller. Let us define the quantities a, b, c, and d as follows:

• a ≡ the month of the year, with March = 1, April = 2, … with January = 11, and February = 12 of the preceding year

• b ≡ the day of the month

• c ≡ the year of the century

• d ≡ the century, though not in the conventional sense. For example, after making adjustments for the months of January and February, for all years like 1910, 1949, 1984, the value of d = 19. And for years like 2003, 2010, 2025, the value of d = 20.

Important: In our calendar, the year begins in January and ends in December. In the calendar, used in the algorithm, the year begins in March and ends in February. Your program should internally make the adjustment and not expect the user to know this. For example, if in our calendar we have January 2009 (month = 1 and year = 2009), the program will make the adjustment so that month = 11 and year = 2008. If you do not make the adjustment you will not get the right result.

For example, 31 July 1929, gives a = 5, b = 31, c = 29, and d = 19. Similarly, 3 January 1988, gives a = 11, b = 3, c = 87, and d = 19.

Now compute the following quantities:

• w = (13 * a - 1 ) / 5

• x = c / 4

• y = d / 4

• z = w + x + y + b + c - 2 * d

• r = z % 7

• r = (r + 7) % 7 [to take care of negative values of r]

r gives the day of the week. r = 0 represents Sunday, r = 1 represents Monday, and so on.

The program that you will be writing will be called Day.py. We will be looking at good documentation, design, and adherence to the coding convention discussed in class. You may use the same variable names used in the problem statement or come up with your own. Your file Day.py have the following header:

```
#  File: Day.py

#  Description:

#  Student Name:

#  Student UT EID:

#  Course Name: CS 303E

#  Unique Number:

#  Date Created: