private static void checkDay(int day, int month, int year) {
		if (notFebruary(month)) {
			if (day >= 1 && day <= DAYS_IN_MONTHS[month]) {
				return;
			}
			throw new IllegalArgumentException("day out of range");
		}

		if (isLeapYear(year)) {
			if (day >= 1 && day <= 29) {
				return;
			}
			throw new IllegalArgumentException("day out of range for Feb");
		}

		if (day >= 1 && day <= 28) {
			return;
		}
		throw new IllegalArgumentException("day out of range for Feb");

	}