-Marked_+0sMarked_-+yx+(0,y)y+(s(x),y)s(+(x,y))-(0,y)0-(x,0)x-(s(x),s(y))-(x,y)+(0,y)y+(s(x),y)s(+(x,y))-(0,y)0-(x,0)x-(s(x),s(y))-(x,y)Marked_+(s(x),y)Marked_+(x,y)Marked_-(s(x),s(y))Marked_-(x,y)+(0,y)y+(s(x),y)s(+(x,y))-(0,y)0-(x,0)x-(s(x),s(y))-(x,y)Marked_+(s(x),y)Marked_+(x,y)Marked_+1Marked_+(s(x),y)Marked_+(x,y)+(0,y)y+(s(x),y)s(+(x,y))-(0,y)0-(x,0)x-(s(x),s(y))-(x,y)+(0,y)y+(s(x),y)s(+(x,y))-(0,y)0-(x,0)x-(s(x),s(y))-(x,y)Marked_-(s(x),s(y))Marked_-(x,y)Marked_-1Marked_-(s(x),s(y))Marked_-(x,y)+(0,y)y+(s(x),y)s(+(x,y))-(0,y)0-(x,0)x-(s(x),s(y))-(x,y)