In a room are 13 men, who are either Knights (truth tellers) or Knaves (lie tellers).

the first man looks around and says "The number of knights in this room is no greater than one"

the second man looks around and says "The number of knights in this room is no greater than two"

the third man looks around and says "The number of knights in this room is no greater than three"

and so on.

**how many knights exactly are in the room?**