($n,$x,$h{0})=<>=~/\d+/g;$y+=$_ for@a=<>=~//g;for$v(@a){$y-=$v;%h=map{$_+$y>=$x?($_,$h{$_}.'x'):(),$_+$v<=$x?($_+$v,$h{$_}.'o'):()}keys%h}print$h{$x}||No