SSC JE Electrical Engineering 26 Sep 2019 Shift 1 Paper

Two statements are given followed by three conclusions numbered I, II and III. Assuming the statements to be true, even if they seem to be at variance with commonly known facts, decide which of the conclusions logically follow(s) from the statements.
Statements:
No customer is manager.
All salesmen are managers.
Conclusions:
I. No salesman is customer.
II. Some managers are salesmen.
III.Some salesmen are customers.