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.

INPUT
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 .

Constraints
1<=N,M,X,Y<= 1000 .
X<=N,Y<=M .
EXAMPLE
Input
5 5
3 2
#**##
****#
****#
****#
**###
Output
YES