Mishnayos Megillah Perek 4 Mishnah 2

On the days of the New Moon and on the intermediate days of a Festival, four people read from the Torah; one may neither decrease the number of readers nor add to them. And one does not conclude with a reading from the Prophets. Both the one who begins the reading and the one who concludes the reading from the Torah recite a blessing. The first reader recites a blessing before the beginning of the reading, and the last reader recites a blessing after its conclusion, but the middle readers do not recite a blessing. The mishna formulates a general principle with regard to the number of people who read from the Torah on different occasions. This is the principle: Any day on which there is an additional offering sacrificed in the Temple and that is not a Festival, i.e., the New Moon and the intermediate days of a Festival, four people read from the Torah; on a Festival, five people read; on Yom Kippur, six people read; and on Shabbat, seven people read. One may not decrease the number of readers, but one may add to them. And on these days one concludes with a reading from the Prophets. Both the one who begins the reading and the one who concludes the reading from the Torah recite a blessing; one recites before the beginning of the reading and one recites after its conclusion, but the middle readers do not recite a blessing.