0Marked_plustimes1Marked_timesplusyxtimes(x,plus(y,1))plus(times(x,plus(y,times(1,0))),x)times(x,1)xplus(x,0)xtimes(x,0)0times(x,plus(y,1))plus(times(x,plus(y,times(1,0))),x)times(x,1)xplus(x,0)xtimes(x,0)0Marked_times(x,plus(y,1))Marked_plus(times(x,plus(y,times(1,0))),x)Marked_times(x,plus(y,1))Marked_times(x,plus(y,times(1,0)))Marked_times(x,plus(y,1))Marked_plus(y,times(1,0))Marked_times(x,plus(y,1))Marked_times(1,0)times(x,plus(y,1))plus(times(x,plus(y,times(1,0))),x)times(x,1)xplus(x,0)xtimes(x,0)0Marked_times(x,plus(y,1))Marked_times(x,plus(y,times(1,0)))plus110Marked_times10110times1000