Points taken off only once for each criteria.

Correctness 40 pts
	
	C1 Backwards subtraction -2
	C2 Backwards division -2
	C3 Incorrect base case (single number expression) -2
	C4 Inability to do double negation (more simply negation of complex expressions) -2
	C5 No check for divide by zero -5
	C6 Incorrect tree construction -4
	C7 Incorrect tree evaluation -4
	C8 Incorrect tree printing -4
	C9 Does not complile -10
	C10 Inability to read non-single digit numbers -5

Style 60
   postfixEval 10
	S1.1 Bad stack implementation (if array used, must resize by constant factors) -3
	S1.2 Stack should be private to stack class -2
	S1.3 Pop, pop, push to eval -2
	S1.4 Did not check for empty stack either by throwing exception in pop or checking
	     manually before pop -3
	
   prefixEval  10
	S2.1 Bad recursive structure -5
	S2.2 Used trees, queues, arrays, etc. -5

   infix stuff 20
	S3.1 Did not use three kinds of trees (zeroary, unary, binary) -10
	     full credit for binary as 1 class or 4.  
	    (-3 instead, for using add, sub, mul ... without binary class)
	S3.2 Did not eval in post-order -3
	S3.3 Did not print in in-order -3
	S3.4 Did not call root's eval/toString in infixEval()/infixString() -4

   exceptions 10
	S4.1 Did not throw appropriately (divide by zero and illegal input) -5
	S4.2 Bad try-catch structure -5

   other 10
	S5.1 Bad control structure to determine cases -3
	S5.2 comments, illegible code, indentation etc. -3
	S5.3 Commented out parts of main (not because it wasn't implemented) -1
	S5.4 Classes not divided into files properly -3

Extra credit 10
	E1 Correctness (div/sub not associative, no extra parens, all
necessary parens, etc.) -5
	   Most people who did the extra credit got the following case
incorrect:
	   For a prefix expression of / * + ~ 1 2 3 + ~ 4 2, the
output should be (~1+2)*3/(~4+2)
	E2 Style (passing current precedence to child) -5