S1 = {4,5,6,1,2,3,4,5} and S2 = {8,9,0,1,5,6,4,5} I need help with the questions below. Please show steps to solve!

3.8. Using the first half of S1 as the alphabet, how many odd numbers you can construct where each element of the alphabet can only appear once? What are these numbers? Note: if S1 is odd, the middle element of S1 is not part of the alphabet. 3.9. Using the second half of S2 as the alphabet, how many even numbers you can construct where each element of the alphabet can only appear once? What are these numbers? Note: if S2 is odd, the middle element of S2 is part of the alphabet