(SETQ ECHO T)
 
(SETQ TRACEFLAG T)
 
(DEFUN TRACE (L)
 (COND (TRACEFLAG (TRACEPRINT L))
  (T NIL)))
 
(DEFUN TRACEPRINT (L)(TERPRI)(PRINC L))
 
(DEFUN INSERT (Z L)
 (COND ((NULL L)(LIST Z))
 ((< (CADR Z)(CADAR L))(CONS Z L))
 (T (CONS(CAR L)(INSERT Z (CDR L))))))
 
(DEFUN SORT (L)
 (COND ((NULL L) L)
 (T (INSERT (CAR L)(SORT (CDR L))))))
 
(DEFUN SEE (A)
 (COND ((NULL A) NIL)
  ((NULL (CDR A)) A)
  ((EQ (CADAR A)(CADADR A))(SEE (CONS (LIST (+ (CAAR A)(CAADR A))(CADAR A))(CDDR A))))
  (T (CONS (CAR A)(SEE (CDR A))))))
 
(DEFUN ZERO (A)
 (COND ((NULL A) A)
  ((EQ (CAAR A) 0)(ZERO (CDR A)))
  (T (CONS (CAR A)(ZERO (CDR A))))))
 
(DEFUN BEGIN (A)(ZERO (SEE (SORT A))))
 
(BEGIN '((8 8)(5 0)(3 2)(-6 8)(7 0)(-3 2)(5 -1)(2 1)(43 3)));
(begin '( () () (0 0)))
(RDS)

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