22.8* There are $n(n>3)$ people, some of whom know each other and some do not, and at least one person does not know everyone else. Question: What is the maximum number of people who know everyone else?
Parse the graph $G$: Use $n$ points to represent these $n$ people, and two vertices are adjacent if and only if the corresponding two people know each other.

Since at least one person does not know everyone else, there are at least two points not adjacent in graph $G$, let $v_{1}, v_{2}$ be not connected by an edge $e-\left(v_{1}, v_{2}\right)$. Then the graph $G$ with the maximum number of edges is $K_{n}-e$, which is the graph obtained by removing edge $e$ from the complete graph $K_{n}$. Thus, the maximum number of vertices adjacent to all other vertices is $n-2$. Therefore, the maximum number of people who know everyone else is $n-2$.