Six students A, B, C, D, E, and F went to the library once last Monday night. One of them stole a book. Each student is questioned about whom they saw at the library, and all tell the truth except the...

Six students A, B, C, D, E, and F went to the library once last Monday night. One of them stole a book. Each student is questioned about whom they saw at the library, and all tell the truth except the thief (it is possible that one student saw another without in turn being seen, but we assume that if one student sees another an arc is drawn with arrow leaving the student who saw the other). That is, A saw B and E; B saw A and F; C saw D and F; D saw A and F; E saw B and C and F saw C and E. Draw a directed graph illustrating the given scenario. If the least number of occurrences being seen at the library makes a person the most probable thief, then who is the thief?