INIT    NTH_TERM = INPUT
        FOUND    = 0
        ITER     = 0
        MODE     = -1
        COUNTER  = 3

DO      REMDR(ITER, 2) 0        :S(EVEN)        F(ODD)
UNTIL
        FOUND NTH_TERM          :S(END)
        ITER     = ITER + 1     :(DO)

EVEN    LT(MODE, 0)             :S(DROP)        F(INCLUDE)
ODD     OUTPUT   = ITER
        FOUND    = FOUND + 1    :(UNTIL)

DROP    COUNTER  = COUNTER - 1
        GT(COUNTER, 0)          :S(UNTIL)
        MODE     = MODE * -1
        COUNTER  = MODE         :(UNTIL)

INCLUDE OUTPUT   = ITER
        FOUND    = FOUND + 1
        COUNTER  = COUNTER - 1
        GT(COUNTER, 0)          :S(UNTIL)
        MODE     = MODE * -2
        COUNTER  = MODE * -1    :(UNTIL)

END