Question 105
Given positive integers $a$, $b$, $n$ such that $a + b = n - 1$. In some school each student has at most $n$ friends from this school. Prove that one can split all the students from this school into two groups: $A$ and $B$, in such a way that every student from the group $A$ will know at most $a$ students from the group $A$, and every student from the group $B$ will know at most $b$ students from the group $B$.
(Anton Trygub)
(Anton Trygub)