Seven boxes, E, F, I, J, R, S and Y, are kept one over the other but not necessarily in the same order. Only F is kept above I. Only E is k…

Seven boxes, E, F, I, J, R, S and Y, are kept one over the other but not necessarily in the same order. Only F is kept above I. Only E is kept between I and R. Only four boxes are kept between I and Y. Only one box is kept between Y and S. How many boxes are kept between J and Y?