Implement hyperexponentiation/tetration without the use of '^' The Challenge

Implement tetration (aka Power Tower or Hyperexponentiation) with the least amount of characters.

The Conditions


Don't use the 'power' operator or its equivalents (such as pow(x,y), x^y, x**y, etc.)
Input given as: x y (separated by a space)
x is exponentiated by itself y times.
Your method must be able to compute at least 4 3 (4 exponentiated by itself 3 times)


The Scoring


Lowest score wins: (# of characters)
Bonus deduction if you do not use the multiplication operator (-5 points).
No Speed/Memory requirements. Take as long as you want.


Examples

x, 0 -&gt; 1

2, 2 -&gt; 2^2 = 4

2, 4 -&gt; 2^(2^(2^2)) = 65536

4, 3 -&gt; 4^(4^4) = 4^256 = 13407807929942597099574024998205846127479365820592393377723561443721764030073546976801874298166903427690031858186486050853753882811946569946433649006084096


Open to suggestions/alterations/questions
J, score is 7 (12 chars - 5 points for avoiding multiplication)
+/@$/@$~/@$~
usage:
   4 +/@$/@$~/@$~ 3
1.34078e154
t=.+/@$/@$~/@$~  NB. define a function
   4 t 3
1.34078e154
   2 t 2
4

Just few nested folds:

Using multiplication it would be */@$~/@$~
Using power it would be ^/@$~ where $~ creates array, / is a fold function.