#! /usr/bin/python
# doomsday.py - A python implementation of Conway's Doomsday algorithm

def set_century(year):
    start_days = (2, 0, 5, 3)
    c = year/100
    x = c % 4
    
    return start_days[x]

def set_year(year):
    y = year % 100
    y12 = y/12
    yr = y % 12
    yr4 = yr/4
    
    return (y12+yr+yr4) % 7

def set_month(month,  year):
    if month % 2:
        if month == 1 :
            if year % 4 == 0:
                mday = 4
            else:
                mday = 3
        else:
            if month in (9,  11):
                mday = month - 4
            else:
                mday = month + 4
    else:
        if month == 2:
            if year % 4 == 0:
                mday = 29
            else:
                mday = 28
        else:
                mday = month
    return mday
                 
def day_offset(month,  day,  year):
    mday = set_month(month,  year)
    offset = (day-mday) % 7
    return offset

def calc_dow(month,  day,  year):
    days = ('Sunday','Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday')
    c = set_century(year)
    y = set_year(year)
    m = day_offset(month,  day,  year)
    dow = days[(c+y+m) % 7]
    return dow