def weekDayInPolish(dayNumber):
    names = {
        0:'Poniedziałek',
        1:'Wtorek',
        2:'Środa',
        3:'Czwartek',
        4:'Piątek',
        5:'Sobota',
        6:'Niedziela'
    }
    return names.get(dayNumber,'error')

print(weekDayInPolish(0))
print(weekDayInPolish(3))
print(weekDayInPolish(8))
