day_of_week.py

y = int(input("Please input year: "))
m = int(input("Please input month: "))
d = int(input("Please input day: "))

step1 = y + (y // 4)
step2 = step1 - (y // 100)
step3 = step2 + (y // 400)
step4 = (m * 13 + 8) // 5
step5 = step3 + step4
step6 = step5 + d
step7 = step6 % 7

if step7 == 0:
    print("Sunday")
elif step7 == 1:
    print("Monday")
elif step7 == 2:
    print("Tuesday")
elif step7 == 3:
    print("Wednesday")
elif step7 == 4:
    print("Thursday")
elif step7 == 5:
    print("Friday")
elif step7 == 6:
    print("Saturday")