This table shows how the first 45 positive integers are distributed in the four classes.

class	contents
p		1	4	7	10	13	16	19	22	25	28	31	34	37	40	43
q		5	11	15	17	23	29	33	35	41	45
s		2	6	8	14	18	20	24	26	32	38	42	44
t		3	9	12	21	27	30	36	39