n=nil;def d(x=@x,y=@y);@n[y]&&@n[y][x];end;def r;o='';File.open("kev.txt").each_line{|l|l.split('').each{|c|if c=="\n";o<<d.to_s;next;end;(dx,dy)={U:[0,-1],D:[0,1],L:[-1,0],R:[1,0]}[c.to_sym];next if !d(@x+dx,@y+dy);@x+=dx;@y+=dy}};o;end;@x=2;@y=2;@n=[[n,n,n],[1,2,3,n],[4,5,6,n],[7,8,9,n]];puts r;@n=[[n,n,n],[n,n,1,n],[n,2,3,4,n],[5,6,7,8,9,n],[n,'A','B','C',n],[n,n,'D',n],[n,n,n]];@x=2;@y=3;puts r