DEF
   I J  INTEGER
ENDDEF

J MGETI
J D1STO
J MGETI
IF J 10513 != THEN 514 ERROR ENDIF
5 INCD1
J MGETI

J I STO

IF I 0 == THEN 515 ERROR ENDIF

WHILE I 1 !=
DO

 I DEC
 J I MUL J STO

ENDWHILE

J PUSH
EXIT