Study the following information carefully and answer the questions given below. Nine persons-K, L, M, N, O, P, Q, R and S purchase different products ...

Study the following information carefully and answer the questions given below. Nine persons-K, L, M, N, O, P, Q, R and S purchase different products one after another but not necessarily in the same order. Three persons purchase products between K and M. R purchase product two persons before M. Two persons purchase product between R and O who purchase product before K. L purchase product just after K. Four persons purchase product between L and Q. The number of persons purchases products before K is same as the number of persons purchase products after Q. P purchase product before S but after M.
Question: How many persons purchase products between O and P?