A certain number of persons are seated in a straight line, all facing north. The following information is given: P sits third to the right of S. - Exa...

A certain number of persons are seated in a straight line, all facing north. The following information is given:

• P sits third to the right of S. - Exactly three persons sit between P and Q. - U sits third to the left of Q. - U is seated fifth from the left end of the row. - R sits third to the left of U. - Exactly three persons sit between W and T, where T is an immediate neighbor of R. - Exactly six persons sit to the right of W. - M sits immediately to the left of O. - Exactly three persons sit between M and H. - O does not sit to the left of P. - H is not seated at either extreme end of the row.
  Question: How many persons sit between U and S?