3. Given a quadrilateral $A B C D$. It is known that $A B=2, B C=4, A D=6, C D=3$. It is also known that at least one of the two diagonals has an integer length. Find what it can be equal to. In your answer, list all suitable values in ascending order separated by a semicolon.
Answer: $4,5,6 \| 4 ; 5 ; 6$