Hey - he spent so much time training suicide bombers maybe the phone was set to blow if anyone dialed the, er, Samaritans. Simon (defun modexpt (x y n) "computes (x^y) mod n" (cond ((= y 0) 1) ((= y 1) (mod x n)) ((evenp y) (mod (expt (modexpt x (/ y 2) n) 2) n)) (t (mod (* x (modexpt x (1- y) n)) n))))