There is a N*M grid . Each cell in grid is either #
or * .# indicates that this position is filled
and * indicates empty positions .
You want to color empty position .You can choose a X*Y sub-grid in which all elements are empty and color it .
You have to tell if all the empty elements of the grid can be colored or not .
Print YES or NO.
First line contains integer N and M .
Second line contains integer X and Y .
Next N lines contains string of M length . OUTPUT
Print YES or NO .