5 Relations
Each for Strong Entity sets : E1 and E2, this contributes +2 (A, B, C) and (D, E, F)
One for M:N type Relationship Set : R, this contributes +1 (A, D)
One relation for each Multi Valued Attribute which preserves Multi Valued Attribute's data : C and F, this contributes +2 (C, C') and (F, F') where C' and F' are the multiple values corresponding to each C and F respectively.
a total of 5 Relations. Here, in all relations the determinant is a super key. So, all are in BCNF and we cannot reduce the number 5 ensuring BCNF.
Ref: http://web.cse.ohio-state.edu/~gurari/course/cse670/cse670Ch9.xht