If a town of an individual became public property, we may make an eruv for its entirety; but if a public [town] became an individual’s, we may not make an eruv for its entirety, unless we exclude [an area] from it equivalent to the town of Chadashah in Judea, which has fifty inhabitants — [these are] the words of R’ Yehudah. R’ Shimon says: Three courtyards containing two dwellings.