Each of A, B, C, D, P, Q and R has an exam on a different day of a week starting from Monday and ending on Sunday of the same week. No one has exam before D. Only three people have exam between D and Q. Only one person has exam between Q and R. B has exam on Wednesday. A has exam on one of the days after C but on one of the days before P. On which day of the week does A have exam?