申論題

一、 Consider the seating arrangement of 5 boys A, B, C, D, and E, and 5 girls F, G, H, I, and J at a round table, where two seating arrangements are considered the same if one of them can be derived from the other by a rotation.

(b)  Prove that in this case, for every seating arrangement, there is always some person both of whose neighbors are boys.