## Subject III (7 p)

Let the set $A=\{\overline{a b c d}, \overline{a b}=\overline{c d}+4\}$

a) Determine whether 2016 and 2024 belong to the set A.

b) Find the remainder of the division of any number from A by 101.

c) If $\mathrm{S}$ is the sum of all numbers in $\mathrm{A}$, show that $\mathrm{S}$ is not a perfect square.