小明要办个聚会,他邀请了他父亲的姐夫,他姐夫的父亲,他哥哥的岳父,他岳父的哥哥。请问他最少邀请了几个人? MjMX1JXBYVnnO32stXtA7e5bi5pAnB8280Np0eLtYuwYUQPX/2CAZ7iNeLARElP4