There are 6 models of a particular product lined up for inspection. The models are identified by the letters A-F. However, they are not necessarily arranged in that order.
The models are distributed among 8 locations, which are identified (from left to right) by the integers 1-8.
The following conditions are known:
(i) Model E is at position 7.
(ii) The two models nearest to E are B and C, and they are on different sides of E.
(iii) Exactly two of the given six models are next to empty locations.
(iv) 3 is not an empty location.
For how many of the 8 locations, can it be said with certainty that a certain model A, B, C, D, E or F exists or that the location is empty?