h,w=map(int,input().split())
p = [input() for i in range(h)]
j=0
for y in range(h):
    for x in range(w):
        if p[y][x]=="#":
            if x>0 and p[y][x-1]=="#":j=1
            elif j==0 and y>0 and p[y-1][x]=="#":j=1
            elif j==0 and x!=w-1 and p[y][x+1]=="#":j=1
            elif j==0 and y!=h-1 and p[y+1][x]=="#":j=1
            if j==0:
                print("No")
                exit()
print("Yes")