import numpy as np

h,w = map(int,input().split())

s = [ list(input()) for i in range(h)]
s = np.array(s)

dy = [-1,0,1,0]
dx = [0,-1,0,1]

print(s.shape)
ans =True

for i in range(0,h):
    for j in range(0,w):
        flag = False
        if s[i][j] == '#' :
            for k in range(4):
                y = i+dy[k]
                x = i+dx[k]
                if  x < 0 or x >=w or y >= h or y < 0 :continue
#                print(x,y)
                if s[x][y] == '#':
                    flag = True

        if flag :ans = False


if ans :print("No")
else:print("Yes")


