General Studies · Box Puzzle

Direction: Study the following information carefully to answer the given question. 7 boxes - P, Q, R, S, T, U and V - are placed one above the other, not necessarily in the same order. Box U is placed third from either of the ends. Box P is placed adjacent to box U. Three boxes are placed between boxes P and S. The number of boxes placed above box S is two more than the number of boxes placed below box V. Box Q is placed above box R, which is not placed below box S. If all the boxes are arranged in alphabetical order from bottom to top, then how many boxes remain unchanged in their position?