Six members A, B, C, D, E and F of a family are travelling together, B' is son of 'C' but 'C' is not the mother of 'B'. 'A' and 'C' is a married couple. 'E' is brother of 'C'. 'D' is daughter of 'A'. 'F' is brother of 'B'. So how many male members are there in the family?