h,w = map(int,input().split())
s = [list(input()) for i in range(h)]
edge = [(0,1),(0,-1),(1,0),(-1,0)]
ans = []
for i in range(h):
    for j in range(w):
        if s[i][j] =="#":
            for x,y in edge:
                if 0<= i+x <w and 0<= j+y < h and s[i+x][j+y] =="#":break #三番目のforから抜け出す
            else:
                print("No")
                break #二番目
    else:continue
    break
else:print("Yes")
