andtrueXactivateXandfalseYfalseiftrueXYactivateXiffalseXYactivateYadd0XactivateXaddsXYsn__addactivateXactivateYfirst0XnilfirstsXconsYZconsactivateYn__firstactivateXactivateZfromXconsactivateXn__fromn__sactivateXaddX1X2n__addX1X2firstX1X2n__firstX1X2fromXn__fromXsXn__sXactivaten__addX1X2addX1X2activaten__firstX1X2firstX1X2activaten__fromXfromXactivaten__sXsXactivateXXandtrueXactivateXiftrueXYactivateXiffalseXYactivateYadd0XactivateXaddsXYactivateYaddsXYactivateXaddsXYsn__addactivateXactivateYfirstsXconsYZactivateZfirstsXconsYZactivateXfirstsXconsYZactivateYfromXactivateXactivaten__addX1X2addX1X2activaten__firstX1X2firstX1X2activaten__fromXfromXactivaten__sXsXtrueandtrueXactivateXfalseiftrueXYactivateXfalseiffalseXYactivateYfalsefromXactivateXactivaten__addX1X2addX1X2add0XactivateXactivaten__firstX1X2firstX1X2firstsXconsYZactivateZactivaten__fromXfromXfirstsXconsYZactivateXfirstsXconsYZactivateYaddsXYactivateYaddsXYactivateXtrue1from1110first2101124add211220activate1110n__from1119n__first2101224cons221428n__add281320s1215002fromXactivateXactivaten__addX1X2addX1X2activaten__firstX1X2firstX1X2fromXactivateXfalseactivaten__firstX1X2firstX1X2falseactivaten__addX1X2addX1X2falseaddsXYsn__addactivateXactivateYfalseactivaten__sXsXfalse